function TreeStyleTabBrowser(aTabBrowser) 
{
	this.mTabBrowser = aTabBrowser;
}
 
TreeStyleTabBrowser.prototype = { 

	kMENUITEM_RELOADSUBTREE            : 'context-item-reloadTabSubTree',
	kMENUITEM_RELOADCHILDREN           : 'context-item-reloadDescendantTabs',
	kMENUITEM_REMOVESUBTREE            : 'context-item-removeTabSubTree',
	kMENUITEM_REMOVECHILDREN           : 'context-item-removeDescendantTabs',
	kMENUITEM_COLLAPSEEXPAND_SEPARATOR : 'context-separator-collapseExpandAll',
	kMENUITEM_COLLAPSE                 : 'context-item-collapseAllSubtree',
	kMENUITEM_EXPAND                   : 'context-item-expandAllSubtree',
	kMENUITEM_AUTOHIDE_SEPARATOR       : 'context-separator-toggleAutoHide',
	kMENUITEM_AUTOHIDE                 : 'context-item-toggleAutoHide',
	kMENUITEM_FIXED                    : 'context-item-toggleFixed',
	kMENUITEM_BOOKMARKSUBTREE          : 'context-item-bookmarkTabSubTree',
	
	mTabBrowser : null, 

	tabbarResizing : false,

	indent          : -1,
	indentProp           : 'margin-left',
	collapseProp         : 'margin-top',
	positionProp         : 'screenY',
	sizeProp             : 'height',
	invertedPositionProp : 'screenX',
	invertedSizeProp     : 'width',

	kVERTICAL_MARGIN_RULES_PATTERN   : /margin-(top|bottom):[^;]+;?/g,
	kHORIZONTAL_MARGIN_RULES_PATTERN : /margin-(left|right):[^;]+;?/g,
	get indentRulesRegExp()
	{
		return this.isVertical ?
				this.kHORIZONTAL_MARGIN_RULES_PATTERN :
				this.kVERTICAL_MARGIN_RULES_PATTERN ;
	},
	get collapseRulesRegExp()
	{
		return this.isVertical ?
				this.kVERTICAL_MARGIN_RULES_PATTERN :
				this.kHORIZONTAL_MARGIN_RULES_PATTERN ;
	},
 
	get browser() 
	{
		return this.mTabBrowser;
	},
 
	get container() 
	{
		if (!this._container) {
			this._container = document.getElementById('appcontent');
		}
		return this._container;
	},
	_container : null,
 
	get scrollBox() 
	{
		if (!this._scrollBox) {
			this._scrollBox = document.getAnonymousElementByAttribute(this.mTabBrowser.mTabContainer, 'class', 'tabs-frame') || // Tab Mix Plus
						this.mTabBrowser.mTabContainer.mTabstrip;
		}
		return this._scrollBox;
	},
	_scrollBox : null,
	get scrollBoxObject()
	{
		return (this.scrollBox.scrollBoxObject || this.scrollBox.boxObject)
				.QueryInterface(Components.interfaces.nsIScrollBoxObject); // Tab Mix Plus
	},
 
/* utils */ 
	
/* get tab contents */ 
	
	getTabLabel : function(aTab) 
	{
		var label = document.getAnonymousElementByAttribute(aTab, 'class', 'tab-text-stack') || // Mac OS X
					document.getAnonymousElementByAttribute(aTab, 'class', 'tab-text-container') || // Tab Mix Plus
					document.getAnonymousElementByAttribute(aTab, 'class', 'tab-text');
		return label;
	},
 
	getTabClosebox : function(aTab) 
	{
		var close = document.getAnonymousElementByAttribute(aTab, 'class', 'tab-close-button always-right') || // Tab Mix Plus
					document.getAnonymousElementByAttribute(aTab, 'class', 'tab-close-button');
		return close;
	},
  
/* status */ 
	
	get isVertical() 
	{
		var b = this.mTabBrowser;
		if (!b) return false;
		var box = this.scrollBox || b.mTabContainer ;
		return (box.getAttribute('orient') || window.getComputedStyle(box, '').getPropertyValue('-moz-box-orient')) == 'vertical';
	},
 
	isTabInViewport : function(aTab) 
	{
		if (!aTab) return false;
		var tabBox = aTab.boxObject;
		var barBox = this.scrollBox.boxObject;
		var xOffset = this.getXOffsetOfTab(aTab);
		var yOffset = this.getYOffsetOfTab(aTab);
		return (tabBox.screenX + xOffset >= barBox.screenX &&
			tabBox.screenX + xOffset + tabBox.width <= barBox.screenX + barBox.width &&
			tabBox.screenY + yOffset >= barBox.screenY &&
			tabBox.screenY + yOffset + tabBox.height <= barBox.screenY + barBox.height);
	},
  
	isMultiRow : function() 
	{
		return false;
	},
  
/* initialize */ 
	
	init : function() 
	{
		var b = this.mTabBrowser;

		this.initTabbar();

		b.addEventListener('TabOpen',        this, true);
		b.addEventListener('TabClose',       this, true);
		b.addEventListener('TabMove',        this, true);
		b.addEventListener('SSTabRestoring', this, true);
		b.mStrip.addEventListener('draggesture', this, false);
		b.mStrip.addEventListener('dragenter', this, false);
		b.mStrip.addEventListener('dragexit', this, false);
		b.mStrip.addEventListener('dragend', this, false);
		b.mStrip.addEventListener('dragover', this, false);
		b.mStrip.addEventListener('dragdrop', this, false);
		b.mTabContainer.addEventListener('mouseover', this, true);
		b.mTabContainer.addEventListener('mouseout', this, true);
		b.mTabContainer.addEventListener('click', this, true);
		b.mTabContainer.addEventListener('dblclick', this, true);
		b.mTabContainer.addEventListener('mousedown', this, true);
		b.mTabContainer.addEventListener('select', this, true);
		b.mTabContainer.addEventListener('scroll', this, true);
		b.mPanelContainer.addEventListener('dragexit', this, false);
		b.mPanelContainer.addEventListener('dragover', this, false);
		b.mPanelContainer.addEventListener('dragdrop', this, false);


		/* Closing collapsed last tree breaks selected tab.
		   To solve this problem, I override the setter to
		   force to set a tab and forbid it becomes null. */
		let (getter, setter) {
			getter = b.__lookupGetter__('selectedTab');
			setter = b.__lookupSetter__('selectedTab');
			eval('setter = '+setter.toSource().replace(
				'{',
				<![CDATA[$&
					if (!val) {
						val = TreeStyleTabService.getLastTab(this);
					}
				]]>.toString()
			));
			/* We have to use both __defineSetter__ and __defineGetter__
			   just in same time!! If we update only setter,
			   getter will be vanished. */
			b.__defineGetter__('selectedTab', getter);
			b.__defineSetter__('selectedTab', setter);
			getter = null;
			setter = null;
		}


		eval('b.mTabContainer._selectNewTab = '+
			b.mTabContainer._selectNewTab.toSource().replace(
				'{',
				<![CDATA[$&
					if (arguments[0].__treestyletab__preventSelect) {
						arguments[0].__treestyletab__preventSelect = false;
						return;
					}
				]]>
			)
		);

		eval('b.mTabContainer.adjustTabstrip = '+
			b.mTabContainer.adjustTabstrip.toSource().replace(
				/(\}\)?)$/,
				<![CDATA[
					var b = TreeStyleTabService.getTabBrowserFromChild(this);
					b.treeStyleTab.updateInvertedTabContentsOrder(true);
				$1]]>
			)
		);

		eval('b.mTabContainer.advanceSelectedTab = '+
			b.mTabContainer.advanceSelectedTab.toSource().replace(
				'{',
				<![CDATA[$&
					var treeStyleTab = TreeStyleTabService.getTabBrowserFromChild(this).treeStyleTab;
					treeStyleTab._focusChangedByShortcut = TreeStyleTabService.accelKeyPressed;
					if (treeStyleTab.getTreePref('focusMode') == treeStyleTab.kFOCUS_VISIBLE) {
						(function(aDir, aWrap, aSelf) {
							var nextTab = (aDir < 0) ? treeStyleTab.getPreviousVisibleTab(aSelf.selectedItem) : treeStyleTab.getNextVisibleTab(aSelf.selectedItem) ;
							if (!nextTab && aWrap) {
								nextTab = TreeStyleTabService.evaluateXPath(
										'child::xul:tab[not(@'+TreeStyleTabService.kCOLLAPSED+'="true")]['+
										(aDir < 0 ? 'last()' : '1' )+
										']',
										aSelf,
										XPathResult.FIRST_ORDERED_NODE_TYPE
									).singleNodeValue;
							}
							if (nextTab && nextTab != aSelf.selectedItem) {
								aSelf._selectNewTab(nextTab, aDir, aWrap);
							}
						})(arguments[0], arguments[1], this);
						return;
					}
				]]>
			)
		);

		eval('b.mTabContainer._handleTabSelect = '+
			b.mTabContainer._handleTabSelect.toSource().replace(
				'{',
				<![CDATA[$&
					if ((function(aTabs) {
							var treeStyleTab = TreeStyleTabService.getTabBrowserFromChild(aTabs).treeStyleTab;
							var tab = aTabs.selectedItem;
							if (!treeStyleTab.isTabInViewport(tab)) {
								treeStyleTab.scrollToTab(tab);
								return true;
							}
							return false;
						})(this)) {
						return;
					}
				]]>
			)
		);

/*
		if ('ensureElementIsVisible' in b.mTabContainer.mTabstrip &&
			'_smoothScrollByPixels' in b.mTabContainer.mTabstrip) {
			eval('b.mTabContainer.mTabstrip.ensureElementIsVisible = '+
				b.mTabContainer.mTabstrip.ensureElementIsVisible.toSource().replace(
					'{',
					<![CDATA[$&
						var browser = TreeStyleTabService.getTabBrowserFromChild(this);
						var startProp = browser.treeStyleTab.isVertical ? 'top' : 'left' ;
						var endProp = browser.treeStyleTab.isVertical ? 'bottom' : 'right' ;
					]]>
				).replace(
					/\.left/g, '[startProp]'
				).replace(
					/\.right/g, '[endProp]'
				).replace(
					'|| this.getAttribute("orient") == "vertical"', ''
				)
			);
			eval('b.mTabContainer.mTabstrip._smoothScrollByPixels = '+
				b.mTabContainer.mTabstrip._smoothScrollByPixels.toSource().replace(
					'{',
					<![CDATA[$&
						var TST = TreeStyleTabService.getTabBrowserFromChild(this);
					]]>
				).replace(
					'scrollBy(distance, 0)',
					<![CDATA[scrollBy(
						(TST.isVertical ? 0 : distance ),
						(TST.isVertical ? distance : 0 )
					)]]>
				)
			);
		}
*/

		eval('b.mTabContainer._notifyBackgroundTab = '+
			b.mTabContainer._notifyBackgroundTab.toSource().replace(
				'{',
				'{ var treeStyleTab = TreeStyleTabService.getTabBrowserFromChild(this).treeStyleTab;'
			).replace(
				/\.screenX/g, '[treeStyleTab.positionProp]'
			).replace(
				/\.width/g, '[treeStyleTab.sizeProp]'
			)
		);

		this.updateTabDNDObserver(b);

		eval('b.getNewIndex = '+
			b.getNewIndex.toSource().replace(
				/\.screenX/g, '[this.treeStyleTab.positionProp]'
			).replace(
				/\.width/g, '[this.treeStyleTab.sizeProp]'
			)
		);

		eval('b.moveTabForward = '+
			b.moveTabForward.toSource().replace(
				'{', '{ var nextTab;'
			).replace(
				'tabPos < this.browsers.length - 1',
				'nextTab = this.treeStyleTab.getNextSiblingTab(this.mCurrentTab)'
			).replace(
				'tabPos + 1', 'nextTab._tPos'
			).replace(
				'this.moveTabTo(',
				<![CDATA[
					var descendant = this.treeStyleTab.getDescendantTabs(nextTab);
					if (descendant.length) {
						nextTab = descendant[descendant.length-1];
					}
					$&]]>
			).replace(
				'this.moveTabToStart();',
				<![CDATA[
					this.treeStyleTab.internallyTabMoving = true;
					var parentTab = this.treeStyleTab.getParentTab(this.mCurrentTab);
					if (parentTab) {
						this.moveTabTo(this.mCurrentTab, this.treeStyleTab.getFirstChildTab(parentTab)._tPos);
						this.mCurrentTab.focus();
					}
					else {
						$&
					}
					this.treeStyleTab.internallyTabMoving = false;
				]]>
			)
		);

		eval('b.moveTabBackward = '+
			b.moveTabBackward.toSource().replace(
				'{', '{ var prevTab;'
			).replace(
				'tabPos > 0',
				'prevTab = this.treeStyleTab.getPreviousSiblingTab(this.mCurrentTab)'
			).replace(
				'tabPos - 1', 'prevTab._tPos'
			).replace(
				'this.moveTabToEnd();',
				<![CDATA[
					this.treeStyleTab.internallyTabMoving = true;
					var parentTab = this.treeStyleTab.getParentTab(this.mCurrentTab);
					if (parentTab) {
						this.moveTabTo(this.mCurrentTab, this.treeStyleTab.getLastChildTab(parentTab)._tPos);
						this.mCurrentTab.focus();
					}
					else {
						$&
					}
					this.treeStyleTab.internallyTabMoving = false;
				]]>
			)
		);

		eval('b._keyEventHandler.handleEvent = '+
			b._keyEventHandler.handleEvent.toSource().replace(
				'this.tabbrowser.moveTabOver(aEvent);',
				<![CDATA[
					if (!this.tabbrowser.treeStyleTab.isVertical ||
						!this.tabbrowser.treeStyleTab.moveTabLevel(aEvent)) {
						$&
					}
				]]>
			).replace(
				'this.tabbrowser.moveTabForward();',
				<![CDATA[
					if (this.tabbrowser.treeStyleTab.isVertical ||
						!this.tabbrowser.treeStyleTab.moveTabLevel(aEvent)) {
						$&
					}
				]]>
			).replace(
				'this.tabbrowser.moveTabBackward();',
				<![CDATA[
					if (this.tabbrowser.treeStyleTab.isVertical ||
						!this.tabbrowser.treeStyleTab.moveTabLevel(aEvent)) {
						$&
					}
				]]>
			)
		);

		eval('b.loadTabs = '+
			b.loadTabs.toSource().replace(
				'var tabNum = ',
				<![CDATA[
					if (this.treeStyleTab.readyToAttachNewTabGroup)
						TreeStyleTabService.readyToOpenChildTab(firstTabAdded || this.selectedTab, true);
					$&]]>
			).replace(
				'if (!aLoadInBackground)',
				<![CDATA[
					if (TreeStyleTabService.checkToOpenChildTab(this))
						TreeStyleTabService.stopToOpenChildTab(this);
					$&]]>
			).replace(
				'this.selectedTab = firstTabAdded;',
				<![CDATA[
					this.selectedTab = aURIs[0].indexOf('about:treestyletab-group') < 0 ?
						firstTabAdded :
						TreeStyleTabService.getNextTab(firstTabAdded) ;
				]]>
			)
		);

		eval('b.createTooltip = '+
			b.createTooltip.toSource().replace(
				'if ("mOverCloseButton" in tn && tn.mOverCloseButton) {',
				<![CDATA[
					if (TreeStyleTabService.getTabBrowserFromChild(tn).treeStyleTab.handleTooltip(event, tn)) {
						return true;
					}
					else $&]]>
			)
		);

		eval('b.onTabBarDblClick = '+
			b.onTabBarDblClick.toSource().replace(
				'aEvent.originalTarget.localName == "box"',
				'/^(box|(arrow)?scrollbox|tabs)$/.test(aEvent.originalTarget.localName)'
			)
		);

		if ('_onDragEnd' in b) {
			eval('b._onDragEnd = '+b._onDragEnd.toSource().replace(
				/(this\._?replaceTabWithWindow\()/,
				'if (this.treeStyleTab.isDraggingAllTabs(draggedTab)) return; $1'
			).replace(
				'{',
				'{ var treeStyleTab = this.treeStyleTab;'
			).replace(
				/window\.screenX/g, 'gBrowser.boxObject.screenX'
			).replace(
				/window\.outerWidth/g, 'gBrowser.boxObject.width'
			).replace(
				/\.screenX/g, '[treeStyleTab.positionProp]'
			).replace(
				/\.width/g, '[treeStyleTab.sizeProp]'
			).replace(
				/\.screenY/g, '[treeStyleTab.invertedPositionProp]'
			).replace(
				/\.height/g, '[treeStyleTab.invertedSizeProp]'
			));
		}

		// https://bugzilla.mozilla.org/show_bug.cgi?id=406216
		if ('_beginRemoveTab' in b) {
			eval('b._beginRemoveTab = '+b._beginRemoveTab.toSource().replace(
				'for (let i = 0; i < l; ++i) {',
				'l = this.mTabs.length; $&'
			));
		}

		let (tabs, i, maxi) {
			tabs = this.getTabs(b);
			for (i = 0, maxi = tabs.snapshotLength; i < maxi; i++)
			{
				this.initTab(tabs.snapshotItem(i));
			}
		}

		this.onPrefChange('extensions.treestyletab.tabbar.style');
		this.onPrefChange('extensions.treestyletab.twisty.style');
		this.onPrefChange('extensions.treestyletab.showBorderForFirstTab');
		this.onPrefChange('extensions.treestyletab.tabbar.invertTabContents');
		this.onPrefChange('extensions.treestyletab.tabbar.invertClosebox');

		var tabContextMenu = document.getAnonymousElementByAttribute(b, 'anonid', 'tabContextMenu');
		tabContextMenu.addEventListener('popupshowing', this, false);
		if (!('MultipleTabService' in window)) {
			window.setTimeout(function(aSelf, aTabBrowser, aPopup) {
				let suffix = '-tabbrowser-'+(aTabBrowser.id || 'instance-'+parseInt(Math.random() * 65000));
				[
					aSelf.kMENUITEM_RELOADSUBTREE,
					aSelf.kMENUITEM_RELOADCHILDREN,
					aSelf.kMENUITEM_REMOVESUBTREE,
					aSelf.kMENUITEM_REMOVECHILDREN,
					aSelf.kMENUITEM_COLLAPSEEXPAND_SEPARATOR,
					aSelf.kMENUITEM_COLLAPSE,
					aSelf.kMENUITEM_EXPAND,
					aSelf.kMENUITEM_AUTOHIDE_SEPARATOR,
					aSelf.kMENUITEM_AUTOHIDE,
					aSelf.kMENUITEM_FIXED,
					aSelf.kMENUITEM_BOOKMARKSUBTREE
				].forEach(function(aID) {
					let item = document.getElementById(aID).cloneNode(true);
					item.setAttribute('id', item.getAttribute('id')+suffix);

					let refNode = void(0);
					let insertAfter = item.getAttribute('multipletab-insertafter');
					if (insertAfter) {
						try {
							eval('refNode = ('+insertAfter+').nextSibling');
						}
						catch(e) {
						}
					}
					let insertBefore = item.getAttribute('multipletab-insertbefore');
					if (refNode === void(0) && insertBefore) {
						try {
							eval('refNode = '+insertBefore);
						}
						catch(e) {
						}
					}
					aPopup.insertBefore(item, refNode || null);
				});
				tabContextMenu = null;
			}, 0, this, b, tabContextMenu);
		}

		let (allTabPopup) {
			allTabPopup = document.getAnonymousElementByAttribute(b.mTabContainer, 'anonid', 'alltabs-popup');
			if (allTabPopup)
				allTabPopup.addEventListener('popupshowing', this, false);
		}

		/* To move up content area on the tab bar, switch tab.
		   If we don't do it, a gray space appears on the content area
		   by negative margin of it. */
		if (b.getAttribute(this.kTABBAR_POSITION) == 'left' &&
			b.getAttribute(this.kSCROLLBAR_INVERTED) == 'true') {
			b.removeTab(
				b.selectedTab = b.addTab('about:blank')
			);
		}

		this.ObserverService.addObserver(this, 'TreeStyleTab:indentModified', false);
		this.ObserverService.addObserver(this, 'TreeStyleTab:collapseExpandAllSubtree', false);
		this.addPrefListener(this);

		// TreeStyleTabBrowserAutoHide fails to initialize before the tab bar is completely initialized!!!
		this.autoHide = new TreeStyleTabBrowserAutoHide(this);

		b = null;
	},
	
	initTab : function(aTab) 
	{
		if (!aTab.hasAttribute(this.kID)) {
			var id = this.getTabValue(aTab, this.kID) || this.makeNewId();
			this.setTabValue(aTab, this.kID, id);
		}

		aTab.__treestyletab__linkedTabBrowser = this.mTabBrowser;

		this.initTabAttributes(aTab);
		this.initTabContents(aTab);

		aTab.setAttribute(this.kNEST, 0);
	},
	ensureTabInitialized : function(aTab)
	{
		if (!aTab || aTab.getAttribute(this.kID)) return;
		this.initTab(aTab);
	},
	
	initTabAttributes : function(aTab) 
	{
		var pos = this.mTabBrowser.getAttribute(this.kTABBAR_POSITION);
		if (pos == 'left' || pos == 'right') {
			aTab.setAttribute('align', 'stretch');
			aTab.removeAttribute('maxwidth');
			aTab.removeAttribute('minwidth');
			aTab.removeAttribute('width');
			aTab.removeAttribute('flex');
			aTab.maxWidth = 65000;
			aTab.minWidth = 0;
			aTab.setAttribute('dir', 'ltr'); // Tab Mix Plus
		}
		else {
			aTab.removeAttribute('align');
			aTab.setAttribute('maxwidth', 250);
			aTab.setAttribute('minwidth', this.mTabBrowser.mTabContainer.mTabMinWidth);
			aTab.setAttribute('width', '0');
			aTab.setAttribute('flex', 100);
			aTab.maxWidth = 250;
			aTab.minWidth = this.mTabBrowser.mTabContainer.mTabMinWidth;
			aTab.removeAttribute('dir'); // Tab Mix Plus
		}
	},
 
	initTabContents : function(aTab) 
	{
		var icon  = document.getAnonymousElementByAttribute(aTab, 'class', 'tab-icon');
		var label = this.getTabLabel(aTab);
		var close = this.getTabClosebox(aTab);
		var counter = document.getAnonymousElementByAttribute(aTab, 'class', this.kCOUNTER_CONTAINER);

		if (!document.getAnonymousElementByAttribute(aTab, 'class', this.kTWISTY)) {
			var twisty = document.createElement('image');
			twisty.setAttribute('class', this.kTWISTY);
			var container = document.createElement('hbox');
			container.setAttribute('class', this.kTWISTY_CONTAINER);
			container.appendChild(twisty);

			icon.appendChild(container);

			var marker = document.createElement('image');
			marker.setAttribute('class', this.kDROP_MARKER);
			container = document.createElement('hbox');
			container.setAttribute('class', this.kDROP_MARKER_CONTAINER);
			container.appendChild(marker);

			icon.appendChild(container);
		}

		if (!counter) {
			var counter = document.createElement('hbox');
			counter.setAttribute('class', this.kCOUNTER_CONTAINER);

			counter.appendChild(document.createElement('label'));
			counter.lastChild.setAttribute('class', this.kCOUNTER);
			counter.lastChild.setAttribute('value', '(0)');

			if (label) {
				label.parentNode.insertBefore(counter, label.nextSibling);
			}
		}
		this.initTabContentsOrder(aTab);
	},
 
	initTabContentsOrder : function(aTab) 
	{
		var label = this.getTabLabel(aTab);
		var close = this.getTabClosebox(aTab);
		var counter = document.getAnonymousElementByAttribute(aTab, 'class', this.kCOUNTER_CONTAINER);
		var inverted = this.mTabBrowser.getAttribute(this.kTAB_CONTENTS_INVERTED) == 'true';

		var nodes = Array.slice(document.getAnonymousNodes(aTab));

		// reset order
		nodes.forEach(function(aNode, aIndex) {
			aNode.setAttribute('ordinal', aIndex);
		}, this);

		// rearrange top-level contents
		nodes.splice(nodes.indexOf(close), 1);
		if (inverted) {
			if (this.mTabBrowser.getAttribute(this.kCLOSEBOX_INVERTED) == 'true')
				nodes.splice(nodes.indexOf(label.parentNode)+1, 0, close);
			else
				nodes.splice(nodes.indexOf(label.parentNode), 0, close);
		}
		else {
			if (this.mTabBrowser.getAttribute(this.kCLOSEBOX_INVERTED) == 'true')
				nodes.splice(nodes.indexOf(label.parentNode), 0, close);
			else
				nodes.splice(nodes.indexOf(label.parentNode)+1, 0, close);
		}
		var count = nodes.length;
		Array.slice(nodes).reverse()
			.forEach(function(aNode, aIndex) {
				aNode.setAttribute('ordinal', (count - aIndex + 1) * 100);
			}, this);

		// rearrange contents in "tab-image-middle"
		nodes = Array.slice(label.parentNode.childNodes);
		nodes.splice(nodes.indexOf(counter), 1);
		if (inverted) nodes.reverse();
		nodes.splice(nodes.indexOf(label)+1, 0, counter);
		count = nodes.length;
		nodes.reverse().forEach(function(aNode, aIndex) {
			if (aNode.getAttribute('class') == 'informationaltab-thumbnail-container')
				return;
			aNode.setAttribute('ordinal', (count - aIndex + 1) * 100);
		}, this);
	},
 
	updateInvertedTabContentsOrder : function(aAll) 
	{
		if (!this.getTreePref('tabbar.invertTabContents')) return;
		window.setTimeout(function(aSelf) {
			var b = aSelf.mTabBrowser;
			var tabs = aAll ? aSelf.getTabsArray(b) : [b.selectedTab] ;
			tabs.forEach(function(aTab) {
				aSelf.initTabContentsOrder(aTab);
			});
			b = null;
			tabs = null;
		}, 0, this);
	},
  
	initTabbar : function(aPosition) 
	{
		if (this.autoHide) this.autoHide.clearTabbarCanvas();

		var b = this.mTabBrowser;

		if (!aPosition) aPosition = this.getTreePref('tabbar.position');
		aPosition = String(aPosition).toLowerCase();

		if (b.getAttribute('id') != 'content' &&
			!this.getTreePref('tabbar.position.subbrowser.enabled')) {
			aPosition = 'top';
		}

		var pos = (aPosition == 'left') ? this.kTABBAR_LEFT :
			(aPosition == 'right') ? this.kTABBAR_RIGHT :
			(aPosition == 'bottom') ? this.kTABBAR_BOTTOM :
			this.kTABBAR_TOP;

		var splitter = document.getAnonymousElementByAttribute(b, 'class', this.kSPLITTER);
		var toggler = document.getAnonymousElementByAttribute(b, 'class', this.kTABBAR_TOGGLER);
		if (!splitter) {
			splitter = document.createElement('splitter');
			splitter.setAttribute('class', this.kSPLITTER);
			splitter.addEventListener('mousedown', this, true);
			splitter.setAttribute('onmouseup', 'TreeStyleTabService.onTabbarResized(event);');
			splitter.setAttribute('state', 'open');
			splitter.appendChild(document.createElement('grippy'));
			var ref = b.mPanelContainer;
			ref.parentNode.insertBefore(splitter, ref);
			toggler = document.createElement('spacer');
			toggler.setAttribute('class', this.kTABBAR_TOGGLER);
			b.mStrip.parentNode.insertBefore(toggler, b.mStrip);
		}

		// Tab Mix Plus
		var scrollFrame = document.getAnonymousElementByAttribute(b.mTabContainer, 'class', 'tabs-frame');
		var newTabBox = document.getAnonymousElementByAttribute(b.mTabContainer, 'id', 'tabs-newbutton-box');
		var tabBarMode = this.getPref('extensions.tabmix.tabBarMode');

		// All-in-One Sidebar
		var toolboxContainer = document.getAnonymousElementByAttribute(b.mStrip, 'anonid', 'aiostbx-toolbox-tableft');
		if (toolboxContainer) toolboxContainer = toolboxContainer.parentNode;

		var scrollInnerBox = b.mTabContainer.mTabstrip._scrollbox ?
				document.getAnonymousNodes(b.mTabContainer.mTabstrip._scrollbox)[0] :
				scrollFrame; // Tab Mix Plus
		var allTabsButton = document.getAnonymousElementByAttribute(b.mTabContainer, 'class', 'tabs-alltabs-button') ||
				document.getAnonymousElementByAttribute(b.mTabContainer, 'anonid', 'alltabs-button'); // Tab Mix Plus

		this.tabbarResizing = false;
		b.removeAttribute(this.kRESIZING);

		b.mStrip.removeAttribute('width');
		b.mPanelContainer.removeAttribute('width');

		var delayedPostProcess;

		if (pos & this.kTABBAR_VERTICAL) {

			this.collapseProp = 'margin-top';
			this.positionProp         = 'screenY';
			this.sizeProp             = 'height';
			this.invertedPositionProp = 'screenX';
			this.invertedSizeProp     = 'width';

			b.mTabBox.orient = splitter.orient = 'horizontal';
			b.mStrip.orient =
				toggler.orient =
				b.mTabContainer.orient =
				b.mTabContainer.mTabstrip.orient =
				b.mTabContainer.mTabstrip.parentNode.orient = 'vertical';
			if (allTabsButton.hasChildNodes()) {
				allTabsButton.firstChild.setAttribute('position', 'before_start');
			}
			b.mTabContainer.setAttribute('align', 'stretch'); // for Mac OS X
			scrollInnerBox.removeAttribute('flex');

			if (scrollFrame) { // Tab Mix Plus
				document.getAnonymousNodes(scrollFrame)[0].removeAttribute('flex');
				scrollFrame.parentNode.orient =
					scrollFrame.orient = 'vertical';
				newTabBox.orient = 'horizontal';
				if (tabBarMode == 2)
					this.setPref('extensions.tabmix.tabBarMode', 1);
			}

			if (toolboxContainer)
				toolboxContainer.orient = 'vertical';

			b.setAttribute(this.kMODE, 'vertical');

			b.mStrip.setAttribute('width', this.getTreePref('tabbar.width'));
			b.mStrip.removeAttribute('height');
			b.mPanelContainer.removeAttribute('height');

			if (pos == this.kTABBAR_RIGHT) {
				b.setAttribute(this.kTABBAR_POSITION, 'right');
				if (this.getTreePref('tabbar.invertTab')) {
					b.setAttribute(this.kTAB_INVERTED, 'true');
					this.indentProp = this.getTreePref('indent.property.right');
				}
				else {
					b.removeAttribute(this.kTAB_INVERTED);
					this.indentProp = this.getTreePref('indent.property.left');
				}
				delayedPostProcess = function(aSelf, aTabBrowser, aSplitter, aToggler) {
					/* in Firefox 3, the width of the rightside tab bar
					   unexpectedly becomes 0 on the startup. so, we have
					   to set the width again. */
					aTabBrowser.mStrip.setAttribute('width', aSelf.getTreePref('tabbar.width'));
					aTabBrowser.mTabDropIndicatorBar.setAttribute('ordinal', 1);
					aTabBrowser.mStrip.setAttribute('ordinal', 30);
					aSplitter.setAttribute('ordinal', 20);
					aToggler.setAttribute('ordinal', 40);
					aTabBrowser.mPanelContainer.setAttribute('ordinal', 10);
					aSplitter.setAttribute('collapse', 'after');
				};
			}
			else {
				b.setAttribute(this.kTABBAR_POSITION, 'left');
				b.removeAttribute(this.kTAB_INVERTED);
				this.indentProp = this.getTreePref('indent.property.left');
				delayedPostProcess = function(aSelf, aTabBrowser, aSplitter, aToggler) {
					aTabBrowser.mTabDropIndicatorBar.setAttribute('ordinal', 1);
					aTabBrowser.mStrip.setAttribute('ordinal', 10);
					aSplitter.setAttribute('ordinal', 20);
					aToggler.setAttribute('ordinal', 5);
					aTabBrowser.mPanelContainer.setAttribute('ordinal', 30);
					aSplitter.setAttribute('collapse', 'before');
				};
			}
		}
		else {
			this.collapseProp         = 'margin-left';
			this.positionProp         = 'screenX';
			this.sizeProp             = 'width';
			this.invertedPositionProp = 'screenY';
			this.invertedSizeProp     = 'height';

			b.mTabBox.orient = splitter.orient = 'vertical';
			b.mStrip.orient =
				toggler.orient =
				b.mTabContainer.orient =
				b.mTabContainer.mTabstrip.orient =
				b.mTabContainer.mTabstrip.parentNode.orient = 'horizontal';
			if (allTabsButton.hasChildNodes()) {
				allTabsButton.firstChild.setAttribute('position', 'after_end');
			}
			b.mTabContainer.removeAttribute('align'); // for Mac OS X
			scrollInnerBox.setAttribute('flex', 1);

			if (scrollFrame) { // Tab Mix Plus
				document.getAnonymousNodes(scrollFrame)[0].setAttribute('flex', 1);
				scrollFrame.parentNode.orient =
					scrollFrame.orient = 'horizontal';
				newTabBox.orient = 'vertical';
			}

			if (toolboxContainer)
				toolboxContainer.orient = 'horizontal';

			b.setAttribute(this.kMODE, this.getTreePref('tabbar.multirow') ? 'multirow' : 'horizontal' );
			b.removeAttribute(this.kTAB_INVERTED);

			if (pos == this.kTABBAR_BOTTOM) {
				b.setAttribute(this.kTABBAR_POSITION, 'bottom');
				this.indentProp = this.getTreePref('indent.property.bottom');
				delayedPostProcess = function(aSelf, aTabBrowser, aSplitter, aToggler) {
					aTabBrowser.mTabDropIndicatorBar.setAttribute('ordinal', 1);
					aTabBrowser.mStrip.setAttribute('ordinal', 30);
					aSplitter.setAttribute('ordinal', 20);
					aToggler.setAttribute('ordinal', 40);
					aTabBrowser.mPanelContainer.setAttribute('ordinal', 10);
				};
			}
			else {
				b.setAttribute(this.kTABBAR_POSITION, 'top');
				this.indentProp = this.getTreePref('indent.property.top');
				delayedPostProcess = function(aSelf, aTabBrowser, aSplitter, aToggler) {
					aTabBrowser.mTabDropIndicatorBar.setAttribute('ordinal', 1);
					aTabBrowser.mStrip.setAttribute('ordinal', 10);
					aSplitter.setAttribute('ordinal', 20);
					aToggler.setAttribute('ordinal', 5);
					aTabBrowser.mPanelContainer.setAttribute('ordinal', 30);
				};
			}
		}

		this.getTabsArray(b).forEach(function(aTab) {
			this.updateTabCollapsed(aTab, aTab.getAttribute(this.kCOLLAPSED) == 'true', true);
		}, this);

		this.updateTabbarState();
		window.setTimeout(function(aSelf, aTabBrowser, aSplitter, aToggler) {
			delayedPostProcess(aSelf, aTabBrowser, aSplitter, aToggler);
			aSelf.updateTabbarOverflow();
			delayedPostProcess = null;
		}, 0, this, b, splitter, toggler);

		b = null;
		pos = null;
		splitter = null;
		toggler = null;
		scrollFrame = null;
		newTabBox = null
		tabBarMode = null;
		toolboxContainer = null;
		scrollInnerBox = null;
		scrollInnerBox = null;
		allTabsButton = null;
	},
	
	updateTabbarState : function() 
	{
		var b = this.mTabBrowser;
		var orient;
		if (this.isVertical) {
			orient = 'vertical';
			if (this.getTreePref('tabbar.fixed.vertical'))
				b.setAttribute(this.kFIXED, true);
			else
				b.removeAttribute(this.kFIXED);
		}
		else {
			orient = 'horizontal';
			if (this.getTreePref('tabbar.fixed.horizontal')) {
				b.setAttribute(this.kFIXED, true);
				if (!this.isMultiRow()) {
					b.mStrip.removeAttribute('height');
					b.mPanelContainer.removeAttribute('height');
				}
			}
			else {
				b.removeAttribute(this.kFIXED);
				b.mStrip.setAttribute('height', this.getTreePref('tabbar.height'));
			}
		}

		if (this.getTreePref('enableSubtreeIndent.'+orient))
			b.setAttribute(this.kINDENTED, 'true');
		else
			b.removeAttribute(this.kINDENTED);

		if (this.getTreePref('allowSubtreeCollapseExpand.'+orient))
			b.setAttribute(this.kALLOW_COLLAPSE, 'true');
		else
			b.removeAttribute(this.kALLOW_COLLAPSE);

		if (this.getTreePref('tabbar.hideNewTabButton.'+orient))
			b.setAttribute(this.kHIDE_NEWTAB, 'true');
		else
			b.removeAttribute(this.kHIDE_NEWTAB);

		if (this.getTreePref('tabbar.hideAlltabsButton.'+orient))
			b.setAttribute(this.kHIDE_ALLTABS, 'true');
		else
			b.removeAttribute(this.kHIDE_ALLTABS);

		this.updateAllTabsIndent();
	},
 
	updateTabbarOverflow : function() 
	{
		var b = this.mTabBrowser;
		b.mTabContainer.removeAttribute('overflow'); // Firefox 3.0.x
		var container = document.getAnonymousElementByAttribute(b.mTabContainer, 'class', 'tabs-container');

		if (!container) return;

		container.removeAttribute('overflow');

		var scrollBox = this.scrollBox;
		scrollBox.addEventListener('overflow', this, true);
		scrollBox.addEventListener('underflow', this, true);
		window.setTimeout(function() {
			scrollBox = document.getAnonymousElementByAttribute(scrollBox, 'anonid', 'scrollbox');
			if (scrollBox) scrollBox = document.getAnonymousNodes(scrollBox)[0];
			if (
				scrollBox &&
				(
					scrollBox.boxObject.width > container.boxObject.width ||
					scrollBox.boxObject.height > container.boxObject.height
				)
				) {
				b.mTabContainer.setAttribute('overflow', true); // Firefox 3.0.x
				container.setAttribute('overflow', true);
			}
			else {
				b.mTabContainer.removeAttribute('overflow'); // Firefox 3.0.x
				container.removeAttribute('overflow');
			}
		}, 100);
	},
   
	destroy : function() 
	{
		this.autoHide.destroy();
		delete this.autoHide;

		var b = this.mTabBrowser;

		this.getTabsArray(b).forEach(function(aTab) {
			this.destroyTab(aTab);
		}, this);

		b.removeEventListener('TabOpen',        this, true);
		b.removeEventListener('TabClose',       this, true);
		b.removeEventListener('TabMove',        this, true);
		b.removeEventListener('SSTabRestoring', this, true);
		b.mStrip.removeEventListener('draggesture', this, false);
		b.mStrip.removeEventListener('dragenter', this, false);
		b.mStrip.removeEventListener('dragexit', this, false);
		b.mStrip.removeEventListener('dragend', this, false);
		b.mStrip.removeEventListener('dragover', this, false);
		b.mStrip.removeEventListener('dragdrop', this, false);
		b.mTabContainer.removeEventListener('click', this, true);
		b.mTabContainer.removeEventListener('dblclick', this, true);
		b.mTabContainer.removeEventListener('mousedown', this, true);
		b.mTabContainer.removeEventListener('select', this, true);
		b.mTabContainer.removeEventListener('scroll', this, true);
		b.mPanelContainer.removeEventListener('dragexit', this, false);
		b.mPanelContainer.removeEventListener('dragover', this, false);
		b.mPanelContainer.removeEventListener('dragdrop', this, false);

		this.tabbarDNDObserver.destroy();
		delete this._tabbarDNDObserver;
		this.panelDNDObserver.destroy();
		delete this._panelDNDObserver;

		this.scrollBox.removeEventListener('overflow', this, true);
		this.scrollBox.removeEventListener('underflow', this, true);

		var tabContextMenu = document.getAnonymousElementByAttribute(b, 'anonid', 'tabContextMenu');
		tabContextMenu.removeEventListener('popupshowing', this, false);

		var allTabPopup = document.getAnonymousElementByAttribute(b.mTabContainer, 'anonid', 'alltabs-popup');
		if (allTabPopup) {
			allTabPopup.removeEventListener('popupshowing', this, false);
		}

		if (this.tabbarCanvas) {
			this.tabbarCanvas.parentNode.removeChild(this.tabbarCanvas);
			this.tabbarCanvas = null;
		}

		this.ObserverService.removeObserver(this, 'TreeStyleTab:indentModified');
		this.ObserverService.removeObserver(this, 'TreeStyleTab:collapseExpandAllSubtree');
		this.removePrefListener(this);

		delete this.mTabBrowser;
		delete this._scrollBox;
	},
	
	destroyTab : function(aTab) 
	{
		delete aTab.__treestyletab__linkedTabBrowser;
	},
   
/* nsIObserver */ 
	
	domains : [ 
		'extensions.treestyletab.'
	],
 
	observe : function(aSubject, aTopic, aData) 
	{
		switch (aTopic)
		{
			case 'TreeStyleTab:indentModified':
				if (this.indent > -1)
					this.updateAllTabsIndent();
				break;

			case 'TreeStyleTab:collapseExpandAllSubtree':
				if (aSubject == window) {
					aData = String(aData);
					this.collapseExpandAllSubtree(
						aData.indexOf('collapse') > -1,
						aData.indexOf('now') > -1
					);
				}
				break;

			case 'nsPref:changed':
				this.onPrefChange(aData);
				break;

			default:
				break;
		}
	},
 
	onPrefChange : function(aPrefName) 
	{
		var b = this.mTabBrowser;
		var value = this.getPref(aPrefName);
		var tabContainer = b.mTabContainer;
		var tabs  = this.getTabsArray(b);
		switch (aPrefName)
		{
			case 'extensions.treestyletab.tabbar.position':
				this.autoHide.onBeforeTabbarPositionChange();
				this.initTabbar();
				tabs.forEach(function(aTab) {
					this.initTabAttributes(aTab);
				}, this);
				tabs.forEach(function(aTab) {
					this.initTabContents(aTab);
				}, this);
				this.autoHide.onAfterTabbarPositionChange();
				window.setTimeout(function(aSelf) {
					aSelf.checkTabsIndentOverflow();
				}, 0, this);
				break;

			case 'extensions.treestyletab.tabbar.invertTab':
			case 'extensions.treestyletab.tabbar.multirow':
				this.initTabbar();
				this.updateAllTabsIndent();
				tabs.forEach(function(aTab) {
					this.initTabContents(aTab);
				}, this);
				break;
			case 'extensions.treestyletab.tabbar.invertTabContents':
				if (value)
					b.setAttribute(this.kTAB_CONTENTS_INVERTED, 'true');
				else
					b.removeAttribute(this.kTAB_CONTENTS_INVERTED);
				tabs.forEach(function(aTab) {
					this.initTabContents(aTab);
				}, this);
				break;

			case 'extensions.treestyletab.tabbar.invertClosebox':
				if (value)
					b.setAttribute(this.kCLOSEBOX_INVERTED, 'true');
				else
					b.removeAttribute(this.kCLOSEBOX_INVERTED);
				tabs.forEach(function(aTab) {
					this.initTabContents(aTab);
				}, this);
				break;

			case 'extensions.treestyletab.tabbar.style':
				if (value) {
					if (/^(default|vertigo|mixed)$/.test(value))
						value = 'square '+value;
					b.setAttribute(this.kSTYLE, value);
				}
				else {
					b.removeAttribute(this.kSTYLE);
				}
				break;

			case 'extensions.treestyletab.twisty.style':
				if (value == 'auto') {
					if (
						window['piro.sakura.ne.jp'].extensions.isAvailable('informationaltab@piro.sakura.ne.jp') &&
						this.getPref('extensions.informationaltab.thumbnail.enabled') &&
						this.getPref('extensions.informationaltab.thumbnail.position') < 100
						) {
						value = 'retro';
					}
					else {
						value = 'modern-black';
					}
				}
				b.setAttribute(this.kTWISTY_STYLE, value);
				break;

			case 'extensions.treestyletab.showBorderForFirstTab':
				if (value)
					b.setAttribute(this.kFIRSTTAB_BORDER, true);
				else
					b.removeAttribute(this.kFIRSTTAB_BORDER);
				break;

			case 'extensions.treestyletab.enableSubtreeIndent.horizontal':
			case 'extensions.treestyletab.allowSubtreeCollapseExpand.horizontal':
			case 'extensions.treestyletab.tabbar.fixed.horizontal':
			case 'extensions.treestyletab.tabbar.hideNewTabButton.horizontal':
			case 'extensions.treestyletab.tabbar.hideAlltabsButton.horizontal':
				if (!this.isVertical) this.updateTabbarState();
				break;

			case 'extensions.treestyletab.enableSubtreeIndent.vertical':
			case 'extensions.treestyletab.allowSubtreeCollapseExpand.vertical':
			case 'extensions.treestyletab.tabbar.fixed.vertical':
			case 'extensions.treestyletab.tabbar.hideNewTabButton.vertical':
			case 'extensions.treestyletab.tabbar.hideAlltabsButton.vertical':
				if (this.isVertical) this.updateTabbarState();
				break;

			case 'extensions.treestyletab.tabbar.width':
			case 'extensions.treestyletab.tabbar.shrunkenWidth':
				if (!this.tabbarResizing && this.isVertical) {
					this.mTabBrowser.mStrip.removeAttribute('width');
					this.mTabBrowser.mStrip.setAttribute(
						'width',
						(
							!this.autoHide.shown &&
							this.autoHide.mode ==  this.autoHide.kMODE_SHRINK
						) ?
							this.getTreePref('tabbar.shrunkenWidth') :
							this.getTreePref('tabbar.width')
					);
				}
				this.checkTabsIndentOverflow();
				break;

			case 'extensions.treestyletab.tabbar.height':
				this._horizontalTabMaxIndentBase = 0;
				this.checkTabsIndentOverflow();
				break;

			default:
				break;
		}
	},
  
/* DOM Event Handling */ 
	
	handleEvent : function(aEvent) 
	{
		switch (aEvent.type)
		{
			case 'TabOpen':
				this.onTabAdded(aEvent);
				return;

			case 'TabClose':
				this.onTabRemoved(aEvent);
				this.updateLastScrollPosition();
				return;

			case 'TabMove':
				this.onTabMove(aEvent);
				return;

			case 'SSTabRestoring':
				this.onTabRestored(aEvent);
				return;

			case 'select':
				this.onTabSelect(aEvent);
				return;

			case 'click':
				if (aEvent.target.ownerDocument == document)
					this.onTabClick(aEvent);
				return;

			case 'dblclick':
				this.onDblClick(aEvent);
				return;

			case 'mousedown':
				this.onMouseDown(aEvent);
				return;

			case 'scroll':
				this.onScroll(aEvent);
				return;

			case 'popupshowing':
				this.onPopupShowing(aEvent);
				return;


			case 'draggesture':
				nsDragAndDrop.startDrag(aEvent, this.tabbarDNDObserver);
				return;

			case 'dragenter':
				nsDragAndDrop.dragEnter(aEvent, this.tabbarDNDObserver);
				return;

			case 'dragexit':
				nsDragAndDrop.dragExit(
					aEvent,
					aEvent.currentTarget == this.mTabBrowser.mStrip ?
						this.tabbarDNDObserver :
						this.panelDNDObserver
				);
				return;

			case 'dragend':
				this.tabbarDNDObserver.onDragEnd(aEvent);
				return;

			case 'dragover':
			case 'dragdrop':
				let (canDrop, observer) {
					if (aEvent.currentTarget == this.mTabBrowser.mStrip) {
						observer = this.tabbarDNDObserver;
						canDrop = true;
					}
					else {
						observer = this.panelDNDObserver;
						canDrop = observer.canDrop(aEvent, this.getCurrentDragSession());
					}
					// don't use nsDragAndDrop if it can't be dropped!!
					// http://piro.sakura.ne.jp/latest/blosxom/mozilla/xul/2007-02-02_splitbrowser-dragdrop.htm
					if (canDrop)
						nsDragAndDrop[aEvent.type == 'dragover' ? 'dragOver' : 'drop' ](aEvent, observer);
				}
				return;


			case 'mouseover':
				if (this.isEventFiredOnTwisty(aEvent))
					aEvent.target.setAttribute(this.kTWISTY_HOVER, true);
				return;

			case 'mouseout':
				if (this.isEventFiredOnTwisty(aEvent))
					aEvent.target.removeAttribute(this.kTWISTY_HOVER);
				return;

			case 'overflow':
			case 'underflow':
				this.onTabbarOverflow(aEvent);
				return;
		}
	},
	lastScrollX : -1,
	lastScrollY : -1,
	
	updateLastScrollPosition : function() 
	{
		if (!this.isVertical) return;
		var x = {}, y = {};
		var scrollBoxObject = this.scrollBoxObject;
		if (!scrollBoxObject) return;
		scrollBoxObject.getPosition(x, y);
		this.lastScrollX = x.value;
		this.lastScrollY = y.value;
	},
  
	onTabAdded : function(aEvent) 
	{
		var tab = aEvent.originalTarget;
		var b   = this.mTabBrowser;

		this.initTab(tab);

		var hasStructure = this.treeStructure && this.treeStructure.length;
		var positionInTree = hasStructure ? this.treeStructure.shift() : -1 ;

		if (this.readyToAttachNewTab) {
			let parent = this.getTabById(this.parentTab);
			if (parent) {
				let tabs = [parent].concat(this.getDescendantTabs(parent));
				parent = (positionInTree > -1 && positionInTree < tabs.length) ? tabs[positionInTree] : parent ;
			}
			if (parent) {
				this.attachTabTo(tab, parent);
			}

			let refTab;
			let newIndex = -1;
			if (hasStructure) {
			}
			else if (this.insertBefore &&
				(refTab = this.getTabById(this.insertBefore))) {
				newIndex = refTab._tPos;
			}
			else if (parent &&
				this.getTreePref('insertNewChildAt') == this.kINSERT_FISRT &&
				this.multipleCount == 0) {
				/* 複数の子タブを一気に開く場合、最初に開いたタブだけを
				   子タブの最初の位置に挿入し、続くタブは「最初の開いたタブ」と
				   「元々最初の子だったタブ」との間に挿入していく */
				newIndex = parent._tPos + 1;
				if (refTab = this.getFirstChildTab(parent))
					this.insertBefore = refTab.getAttribute(this.kID);
			}

			if (newIndex > -1) {
				if (newIndex > tab._tPos) newIndex--;
				this.internallyTabMoving = true;
				b.moveTabTo(tab, newIndex);
				this.internallyTabMoving = false;
			}
		}

		if (!this.readyToAttachMultiple) {
			this.stopToOpenChildTab(b);
		}
		else {
			this.multipleCount++;
		}

		if (this.animationEnabled) {
			this.updateTabCollapsed(tab, true, true);
			this.updateTabCollapsed(tab, false, !this.completelyRestored);
		}

		var prev = this.getPreviousSiblingTab(tab);
		if (prev)
			this.setTabValue(prev, this.kINSERT_BEFORE, tab.getAttribute(this.kID));

		var next = this.getNextSiblingTab(tab);
		if (next)
			this.setTabValue(next, this.kINSERT_AFTER, tab.getAttribute(this.kID));

		this.autoHide.showTabbarForFeedback();
	},
 
	onTabRemoved : function(aEvent) 
	{
		var tab = aEvent.originalTarget;
		var b   = this.mTabBrowser;

		this.stopTabIndentAnimation(tab);
		this.stopTabCollapseAnimation(tab);
		this.destroyTab(tab);

		var closeParentBehavior = this.getTreePref('closeParentBehavior');
		var closeRootBehavior = this.getTreePref('closeRootBehavior');

		if (
			closeParentBehavior == this.CLOSE_PARENT_BEHAVIOR_CLOSE ||
			tab.getAttribute(this.kSUBTREE_COLLAPSED) == 'true'
			) {
			this.getDescendantTabs(tab).reverse().forEach(function(aTab) {
				b.removeTab(aTab);
			}, this);

			if (this.getTabs(b).snapshotLength == 1) { // this is the last tab
				b.addTab('about:blank');
			}
		}

		var firstChild     = this.getFirstChildTab(tab);
		var parentTab      = this.getParentTab(tab);
		var nextFocusedTab = null;

		var prev = this.getPreviousSiblingTab(tab);
		var next = this.getNextSiblingTab(tab);
		if (prev) {
			this.setTabValue(tab, this.kINSERT_AFTER, prev.getAttribute(this.kID));

			if (next)
				this.setTabValue(prev, this.kINSERT_BEFORE, next.getAttribute(this.kID));
			else
				this.deleteTabValue(prev, this.kINSERT_BEFORE);
		}
		if (next) {
			this.setTabValue(tab, this.kINSERT_BEFORE, next.getAttribute(this.kID));

			if (prev)
				this.setTabValue(next, this.kINSERT_AFTER, prev.getAttribute(this.kID));
			else
				this.deleteTabValue(next, this.kINSERT_AFTER);
		}

		var backupAttributes = {};
		var indentModifiedTabs = [];

		if (firstChild) {
			backupAttributes[this.kCHILDREN] = this.getTabValue(tab, this.kCHILDREN);
			let children   = this.getChildTabs(tab);
			children.forEach((
				(closeParentBehavior == this.CLOSE_PARENT_BEHAVIOR_DETACH) ?
					function(aTab) {
						indentModifiedTabs.push(aTab);
						this.partTab(aTab, {
							dontUpdateIndent : true
						});
						this.moveTabSubTreeTo(aTab, this.getLastTab(b)._tPos);
					} :
				(parentTab ?
					(
						closeParentBehavior == this.CLOSE_PARENT_BEHAVIOR_ESCALATE_FIRST &&
						this.getChildTabs(parentTab).length > 1
					) :
					closeRootBehavior   == this.CLOSE_ROOT_BEHAVIOR_ESCALATE_FIRST
				) ?
					function(aTab, aIndex) {
						this.partTab(aTab, { dontUpdateIndent : true });
						if (aIndex == 0) {
							nextFocusedTab = aTab;
							indentModifiedTabs.push(aTab);
							if (parentTab) {
								this.attachTabTo(aTab, parentTab, {
									dontUpdateIndent : true,
									dontExpand       : true,
									dontMove         : true
								});
							}
						}
						else {
							this.attachTabTo(aTab, children[0], {
								dontUpdateIndent : true,
								dontExpand       : true,
								dontMove         : true
							});
						}
					} :
				parentTab ?
					function(aTab) {
						indentModifiedTabs.push(aTab);
						this.attachTabTo(aTab, parentTab, {
							dontUpdateIndent : true,
							dontExpand       : true,
							dontMove         : true
						});
					} :
					function(aTab) {
						indentModifiedTabs.push(aTab);
						this.partTab(aTab, { dontUpdateIndent : true });
					}
			), this);
			if (closeParentBehavior == this.CLOSE_PARENT_BEHAVIOR_ESCALATE_ALL ||
				closeParentBehavior == this.CLOSE_PARENT_BEHAVIOR_ESCALATE_FIRST)
				nextFocusedTab = firstChild;
		}

		if (parentTab) {
			let firstSibling = this.getFirstChildTab(parentTab);
			let lastSibling  = this.getLastChildTab(parentTab);
			if (tab == lastSibling && !nextFocusedTab) {
				if (tab == firstSibling) { // there is only one child
					nextFocusedTab = parentTab;
				}
				else { // previous sibling tab
					nextFocusedTab = this.getPreviousSiblingTab(tab);
				}
			}

			let ancestors = [],
				ancestor = parentTab;
			do {
				ancestors.push(ancestor.getAttribute(this.kID));
				if (!next && (next = this.getNextSiblingTab(ancestor)))
					backupAttributes[this.kINSERT_BEFORE] = next.getAttribute(this.kID);
			}
			while (ancestor = this.getParentTab(ancestor));
			backupAttributes[this.kANCESTOR] = ancestors.join('|');

			let shouldCloseParentTab = (
					this.isGroupTab(parentTab) &&
					this.getDescendantTabs(parentTab).length == 1
				);
			if (shouldCloseParentTab && nextFocusedTab == parentTab)
				nextFocusedTab = this.getNextFocusedTab(parentTab);

			this.partTab(tab, { dontUpdateIndent : true });

			if (shouldCloseParentTab) {
				window.setTimeout(function() {
					if (parentTab.parentNode)
						b.removeTab(parentTab);
					parentTab = null;
					b = null;
				}, 0);
			}
		}
		else if (!nextFocusedTab) {
			nextFocusedTab = this.getNextFocusedTab(tab);
		}

		if (b.selectedTab == tab) {
			this._focusChangedByCurrentTabRemove = true;
			if (
				nextFocusedTab &&
				this._tabFocusAllowance.every(function(aFunc) {
					return aFunc.call(this, b);
				}, this)
				)
				b.selectedTab = nextFocusedTab;
		}

		if (indentModifiedTabs.length)
			this.updateTabsIndentWithDelay(indentModifiedTabs);
		this.checkTabsIndentOverflow();
		this.autoHide.showTabbarForFeedback();

		for (var i in backupAttributes)
		{
			this.setTabValue(tab, i, backupAttributes[i]);
		}
	},
	CLOSE_PARENT_BEHAVIOR_ESCALATE_FIRST : 3,
	CLOSE_PARENT_BEHAVIOR_ESCALATE_ALL   : 0,
	CLOSE_PARENT_BEHAVIOR_DETACH         : 1,
	CLOSE_PARENT_BEHAVIOR_CLOSE          : 2,
	CLOSE_ROOT_BEHAVIOR_ESCALATE_FIRST : 3,
	CLOSE_ROOT_BEHAVIOR_DETACH         : 1,
	getNextFocusedTab : function(aTab)
	{
		return this.getNextSiblingTab(aTab) ||
				this.getPreviousVisibleTab(aTab);
	},
 
	onTabMove : function(aEvent) 
	{
		var tab = aEvent.originalTarget;
		var b   = this.mTabBrowser;
		this.initTabContents(tab); // twisty vanished after the tab is moved!!

		if (this.hasChildTabs(tab) && !this.isSubTreeMoving) {
			this.moveTabSubTreeTo(tab, tab._tPos);
		}

		var parentTab = this.getParentTab(tab);
		if (parentTab && !this.isSubTreeChildrenMoving) {
			this.updateChildrenArray(parentTab);
		}

		this.updateTabsCount(tab, true);

		var prev = this.getPreviousSiblingTab(tab);
		if (prev)
			this.setTabValue(tab, this.kINSERT_AFTER, prev.getAttribute(this.kID));
		else
			this.deleteTabValue(tab, this.kINSERT_AFTER);

		var next = this.getNextSiblingTab(tab);
		if (next)
			this.setTabValue(tab, this.kINSERT_BEFORE, next.getAttribute(this.kID));
		else
			this.deleteTabValue(tab, this.kINSERT_BEFORE);

		var old = aEvent.detail;
		if (old > tab._tPos) old--;
		old = this.getTabs(b).snapshotItem(old);

		prev = this.getPreviousSiblingTab(old);
		if (prev)
			this.setTabValue(old, this.kINSERT_AFTER, prev.getAttribute(this.kID));
		else
			this.deleteTabValue(old, this.kINSERT_AFTER);

		next = this.getNextSiblingTab(old);
		if (next)
			this.setTabValue(old, this.kINSERT_BEFORE, next.getAttribute(this.kID));
		else
			this.deleteTabValue(old, this.kINSERT_BEFORE);

		if (
			this.isSubTreeMoving ||
			this.internallyTabMoving
			)
			return;

		this.attachTabFromPosition(tab, aEvent.detail);

		this.autoHide.showTabbarForFeedback();
	},
	
	attachTabFromPosition : function(aTab, aOldPosition) 
	{
		var parent = this.getParentTab(aTab);

		if (aOldPosition === void(0)) aOldPosition = aTab._tPos;

		var pos = this.getChildIndex(aTab, parent);
		var oldPos = this.getChildIndex(this.getTabs(this.mTabBrowser).snapshotItem(aOldPosition), parent);
		var delta;
		if (pos == oldPos) { // no move?
			return;
		}
		else if (pos < 0 || oldPos < 0) {
			delta = 2;
		}
		else {
			delta = Math.abs(pos - oldPos);
		}

		var prevTab = this.getPreviousTab(aTab);
		var nextTab = this.getNextTab(aTab);

		var tabs = this.getDescendantTabs(aTab);
		if (tabs.length) {
			nextTab = this.getNextTab(tabs[tabs.length-1]);
		}

		var prevParent = this.getParentTab(prevTab);
		var nextParent = this.getParentTab(nextTab);

		var prevLevel  = prevTab ? Number(prevTab.getAttribute(this.kNEST)) : -1 ;
		var nextLevel  = nextTab ? Number(nextTab.getAttribute(this.kNEST)) : -1 ;

		var newParent;

		if (!prevTab) { // moved to topmost position
			newParent = null;
		}
		else if (!nextTab) { // moved to last position
			newParent = (delta > 1) ? prevParent : parent ;
		}
		else if (prevParent == nextParent) { // moved into existing tree
			newParent = prevParent;
		}
		else if (prevLevel > nextLevel) { // moved to end of existing tree
			if (this.mTabBrowser.selectedTab != aTab) { // maybe newly opened tab
				newParent = prevParent;
			}
			else { // maybe drag and drop
				var realDelta = Math.abs(aTab._tPos - aOldPosition);
				newParent = realDelta < 2 ? prevParent : (parent || nextParent) ;
			}
		}
		else if (prevLevel < nextLevel) { // moved to first child position of existing tree
			newParent = parent || nextParent;
		}

		if (newParent != parent) {
			if (newParent)
				this.attachTabTo(aTab, newParent, { insertBefore : nextTab });
			else
				this.partTab(aTab);
		}
	},
 
	updateChildrenArray : function(aTab) 
	{
		var children = this.getChildTabs(aTab);
		children.sort(function(aA, aB) { return aA._tPos - aB._tPos; });
		this.setTabValue(
			aTab,
			this.kCHILDREN,
			children
				.map(function(aItem) {
					return aItem.getAttribute(this.kID);
				}, this)
				.join('|')
		);
	},
  
	onTabRestored : function(aEvent) 
	{
		this.restoreStructure(aEvent.originalTarget, !this.completelyRestored);
	},
	restoreStructure : function(aTab, aWithoutAnimation)
	{
		var tab = aTab;
		var b   = this.mTabBrowser;

		var maybeDuplicated = false;

		var id = this.getTabValue(tab, this.kID);

		if (this.getTabById(id)) { // this is a duplicated tab!
			maybeDuplicated = true;
			id = this.redirectId(id);
		}

		if (!maybeDuplicated) {
			/* If it has a parent, it is wrongly attacched by tab moving
			   on restoring. Restoring the old ID (the next statement)
			   breaks the children list of the temporary parent and causes
			   many problems. So, to prevent these problems, I part the tab
			   from the temporary parent manually. */
			this.partTab(tab, {
				dontUpdateIndent : true,
				dontAnimate      : aWithoutAnimation
			});
			/* reset attributes before restoring */
			tab.removeAttribute(this.kID);
			tab.removeAttribute(this.kPARENT);
			tab.removeAttribute(this.kCHILDREN);
			tab.removeAttribute(this.kSUBTREE_COLLAPSED);
			tab.removeAttribute(this.kCOLLAPSED);
			tab.removeAttribute(this.kNEST);
			this.updateTabsIndent([tab], undefined, undefined, aWithoutAnimation);
		}

		this.setTabValue(tab, this.kID, id);

		var isSubTreeCollapsed = (this.getTabValue(tab, this.kSUBTREE_COLLAPSED) == 'true');

		var children = this.getTabValue(tab, this.kCHILDREN);
		var tabs = [];
		if (children) {
			tab.removeAttribute(this.kCHILDREN);
			children = children.split('|');
			if (maybeDuplicated)
				children = children.map(function(aChild) {
					return this.redirectId(aChild);
				}, this);
			children.forEach(function(aTab) {
				if (aTab && (aTab = this.getTabById(aTab))) {
					this.attachTabTo(aTab, tab, {
						dontExpand       : true,
						dontUpdateIndent : true,
						dontAnimate      : aWithoutAnimation
					});
					tabs.push(aTab);
				}
			}, this);
		}

		var nextTab = this.getTabValue(tab, this.kINSERT_BEFORE);
		if (nextTab && maybeDuplicated) nextTab = this.redirectId(nextTab);
		nextTab = this.getTabById(nextTab);

		if (!nextTab) {
			var prevTab = this.getTabValue(tab, this.kINSERT_AFTER);
			if (prevTab && maybeDuplicated) prevTab = this.redirectId(prevTab);
			nextTab = this.getNextSiblingTab(this.getTabById(prevTab));
		}

		var ancestors = (this.getTabValue(tab, this.kANCESTOR) || this.getTabValue(tab, this.kPARENT)).split('|');
		var parent = null;
		for (var i in ancestors)
		{
			if (maybeDuplicated) ancestors[i] = this.redirectId(ancestors[i]);
			parent = this.getTabById(ancestors[i]);
			if (parent) {
				parent = ancestors[i];
				break;
			}
		}
		this.deleteTabValue(tab, this.kANCESTOR);

		if (parent) {
			tab.removeAttribute(this.kPARENT);
			parent = this.getTabById(parent);
			if (parent) {
				this.attachTabTo(tab, parent, {
					dontExpand       : true,
					insertBefore     : nextTab,
					dontUpdateIndent : true,
					dontAnimate      : aWithoutAnimation
				});
				this.updateTabsIndent([tab], undefined, undefined, aWithoutAnimation);
				this.checkTabsIndentOverflow();
			}
			else {
				this.deleteTabValue(tab, this.kPARENT);
			}
		}
		else if (children) {
			this.updateTabsIndent(tabs, undefined, undefined, aWithoutAnimation);
			this.checkTabsIndentOverflow();
		}

		if (!parent) {
			if (!nextTab) nextTab = this.getNextTab(tab);
			var parentOfNext = this.getParentTab(nextTab);
			var newPos = -1;
			if (parentOfNext) {
				var descendants = this.getDescendantTabs(parentOfNext);
				newPos = descendants[descendants.length-1]._tPos;
			}
			else if (nextTab) {
				var newPos = nextTab._tPos;
				if (newPos > tab._tPos) newPos--;
			}
			if (newPos > -1)
				b.moveTabTo(tab, newPos);
		}

		if (isSubTreeCollapsed) {
			this.collapseExpandSubtree(tab, isSubTreeCollapsed, aWithoutAnimation);
		}

		if (maybeDuplicated) this.clearRedirectionTable();
	},
	
	redirectId : function(aId) 
	{
		if (!(aId in this._redirectionTable))
			this._redirectionTable[aId] = this.makeNewId();
		return this._redirectionTable[aId];
	},
	_redirectionTable : {},
 
	clearRedirectionTable : function() 
	{
		if (this._clearRedirectionTableTimer) {
			window.clearTimeout(this._clearRedirectionTableTimer);
			this._clearRedirectionTableTimer = null;
		}
		this._clearRedirectionTableTimer = window.setTimeout(function(aSelf) {
			aSelf._redirectionTable = {};
		}, 1000, this);
	},
	_clearRedirectionTableTimer : null,
  
	onTabSelect : function(aEvent) 
	{
		var b   = this.mTabBrowser;
		var tab = b.selectedTab

		if (tab.getAttribute(this.kCOLLAPSED) == 'true') {
			if (this.getTreePref('autoExpandSubTreeOnCollapsedChildFocused')) {
				var parentTab = tab;
				while (parentTab = this.getParentTab(parentTab))
				{
					this.collapseExpandSubtree(parentTab, false);
				}
				this.collapseExpandTreesIntelligentlyWithDelayFor(tab);
			}
			else {
				b.selectedTab = this.getRootTab(tab);
			}
		}
		else if (
				this.getTreePref('autoCollapseExpandSubTreeOnSelect') &&
				(
					!this._focusChangedByCurrentTabRemove ||
					this.getTreePref('autoCollapseExpandSubTreeOnSelect.onCurrentTabRemove')
				)
				) {
			if (!this.hasChildTabs(tab) || (tab.getAttribute(this.kSUBTREE_COLLAPSED) != 'true'))
				tab = null;

			if (
				this._focusChangedByShortcut &&
				this.accelKeyPressed &&
				!this.getTreePref('autoCollapseExpandSubTreeOnSelect.whileFocusMovingByShortcut')
				) {
				TreeStyleTabService.expandTreeAfterKeyReleased(tab);
			}
			else {
				this.collapseExpandTreesIntelligentlyWithDelayFor(tab);
			}
		}

		this._focusChangedByCurrentTabRemove = false;
		this._focusChangedByShortcut = false;

		this.updateInvertedTabContentsOrder();

		this.autoHide.onTabSelect();
	},
 
	onTabClick : function(aEvent) 
	{
		if (aEvent.button != 0) return;

		if (this.isEventFiredOnTwisty(aEvent)) {
			var tab = this.getTabFromEvent(aEvent);
			if (this.hasChildTabs(tab) &&
				this.mTabBrowser.getAttribute(this.kALLOW_COLLAPSE) == 'true') {
				this.collapseExpandSubtree(tab, tab.getAttribute(this.kSUBTREE_COLLAPSED) != 'true');
				aEvent.preventDefault();
				aEvent.stopPropagation();
			}
		}
		else if (!this.getTabFromEvent(aEvent)) {
			var tab = this.getTabFromTabbarEvent(aEvent);
			if (tab) this.mTabBrowser.selectedTab = tab;
		}
	},
	getTabFromTabbarEvent : function(aEvent)
	{
		if (
			!this.shouldDetectClickOnIndentSpaces ||
			this.isEventFiredOnClickable(aEvent)
			)
			return null;

		var tab = null;
		var clickedPoint = aEvent[this.positionProp];
		this.getTabsArray(this.mTabBrowser).some(function(aTab) {
			var box = aTab.boxObject;
			if (box[this.positionProp] > clickedPoint ||
				box[this.positionProp] + box[this.sizeProp] < clickedPoint) {
				return false;
			}
			tab = aTab;
			return true;
		}, this);
		return tab;
	},
 
	onDblClick : function(aEvent) 
	{
		var tab = this.getTabFromEvent(aEvent);
		if (tab &&
			this.hasChildTabs(tab) &&
			this.getTreePref('collapseExpandSubTree.dblclick')) {
			this.collapseExpandSubtree(tab, tab.getAttribute(this.kSUBTREE_COLLAPSED) != 'true');
			aEvent.preventDefault();
			aEvent.stopPropagation();
		}
	},
 
	onMouseDown : function(aEvent) 
	{
		if (aEvent.button != 0 ||
			!this.isEventFiredOnTwisty(aEvent))
			return;

		this.getTabFromEvent(aEvent).__treestyletab__preventSelect = true;
	},
 
	onScroll : function(aEvent) 
	{
		var node = aEvent.originalTarget;
		if (node && node.ownerDocument == document) {
			if (this.lastScrollX < 0 || this.lastScrollY < 0) return;
			var x = {}, y = {};
			var scrollBoxObject = this.scrollBoxObject;
			scrollBoxObject.getPosition(x, y);
			if (x.value != this.lastScrollX || y.value != this.lastScrollY)
				scrollBoxObject.scrollTo(this.lastScrollX, this.lastScrollY);
			this.lastScrollX = -1;
			this.lastScrollY = -1;
		}
	},
 
	onTabbarOverflow : function(aEvent) 
	{
		var tabs = this.mTabBrowser.mTabContainer;
		var horizontal = tabs.orient == 'horizontal';
		if (horizontal) return;
		aEvent.stopPropagation();
		if (aEvent.detail == 1) return;
		if (aEvent.type == 'overflow') {
			tabs.setAttribute('overflow', 'true');
			this.scrollBoxObject.ensureElementIsVisible(tabs.selectedItem);
		}
		else {
			tabs.removeAttribute('overflow');
		}
	},
 
	onPopupShowing : function(aEvent) 
	{
		if (aEvent.target != aEvent.currentTarget) return;
		switch (aEvent.target.getAttribute('anonid'))
		{
			case 'tabContextMenu':
				this.initTabContextMenu(aEvent);
				break;
			case 'alltabs-popup':
				this.initAllTabsPopup(aEvent);
				break;
		}
	},
	
	initTabContextMenu : function(aEvent) 
	{
		var b = this.mTabBrowser;
		var sep, items = {};

		[
			this.kMENUITEM_RELOADSUBTREE,
			this.kMENUITEM_RELOADCHILDREN,
			this.kMENUITEM_REMOVESUBTREE,
			this.kMENUITEM_REMOVECHILDREN,
			this.kMENUITEM_COLLAPSE,
			this.kMENUITEM_EXPAND,
			this.kMENUITEM_AUTOHIDE,
			this.kMENUITEM_FIXED,
			this.kMENUITEM_BOOKMARKSUBTREE
		].forEach(function(aID) {
			let item = this.evaluateXPath(
				'descendant::xul:*[starts-with(@id, "'+aID+'")]',
				aEvent.currentTarget,
				XPathResult.FIRST_ORDERED_NODE_TYPE
			).singleNodeValue;
			items[aID] = item;
			if (this.getTreePref('show.'+aID))
				item.removeAttribute('hidden');
			else
				item.setAttribute('hidden', true);
			switch (aID)
			{
				case this.kMENUITEM_RELOADSUBTREE:
				case this.kMENUITEM_RELOADCHILDREN:
				case this.kMENUITEM_REMOVESUBTREE:
				case this.kMENUITEM_REMOVECHILDREN:
				case this.kMENUITEM_COLLAPSE:
				case this.kMENUITEM_EXPAND:
				case this.kMENUITEM_BOOKMARKSUBTREE:
					this.showHideSubTreeMenuItem(item, [b.mContextTab]);
					break;
				default:
					break;
			}
		}, this);

		// collapse/expand all
		sep = this.evaluateXPath(
			'descendant::xul:menuseparator[starts-with(@id, "'+this.kMENUITEM_COLLAPSEEXPAND_SEPARATOR+'")]',
			aEvent.currentTarget,
			XPathResult.FIRST_ORDERED_NODE_TYPE
		).singleNodeValue;
		let collapseItem = items[this.kMENUITEM_COLLAPSE];
		let expanndItem = items[this.kMENUITEM_EXPAND];
		if (this.evaluateXPath(
				'child::xul:tab[@'+this.kCHILDREN+']',
				b.mTabContainer
			).snapshotLength) {
			if (this.evaluateXPath(
					'child::xul:tab[@'+this.kCHILDREN+' and not(@'+this.kSUBTREE_COLLAPSED+'="true")]',
					b.mTabContainer
				).snapshotLength)
				collapseItem.removeAttribute('disabled');
			else
				collapseItem.setAttribute('disabled', true);

			if (this.evaluateXPath(
					'child::xul:tab[@'+this.kCHILDREN+' and @'+this.kSUBTREE_COLLAPSED+'="true"]',
					b.mTabContainer
				).snapshotLength)
				expanndItem.removeAttribute('disabled');
			else
				expanndItem.setAttribute('disabled', true);
		}
		else {
			collapseItem.setAttribute('hidden', true);
			expanndItem.setAttribute('hidden', true);
		}
		if (collapseItem.getAttribute('hidden') == 'true' &&
			expanndItem.getAttribute('hidden') == 'true') {
			sep.setAttribute('hidden', true);
		}
		else {
			sep.removeAttribute('hidden');
		}

		// auto hide
		let autohide = items[this.kMENUITEM_AUTOHIDE];
		this.autoHide.updateAutoHideMenuItem(autohide);

		// fix
		let fixedPref;
		let fixedLabel;
		if (this.isVertical) {
			fixedPref = 'tabbar.fixed.vertical';
			fixedLabel = 'label-vertical';
		}
		else {
			fixedPref = 'tabbar.fixed.horizontal';
			fixedLabel = 'label-horizontal';
		}
		let fixed = items[this.kMENUITEM_FIXED];
		fixed.setAttribute('label', fixed.getAttribute(fixedLabel));
		if (this.getTreePref(fixedPref))
			fixed.setAttribute('checked', true);
		else
			fixed.removeAttribute('checked');

		sep = this.evaluateXPath(
			'descendant::xul:menuseparator[starts-with(@id, "'+this.kMENUITEM_AUTOHIDE_SEPARATOR+'")]',
			aEvent.currentTarget,
			XPathResult.FIRST_ORDERED_NODE_TYPE
		).singleNodeValue;
		if (autohide.getAttribute('hidden') != 'true' ||
			fixed.getAttribute('hidden') != 'true') {
			sep.removeAttribute('hidden');
		}
		else {
			sep.setAttribute('hidden', true);
		}
	},
 
	initAllTabsPopup : function(aEvent) 
	{
		if (!this.getTreePref('enableSubtreeIndent.allTabsPopup')) return;
		var items = aEvent.target.childNodes;
		var tabs = this.getTabs(this.mTabBrowser);
		for (var i = 0, maxi = items.length; i < maxi; i++)
		{
			items[i].style.paddingLeft = tabs.snapshotItem(i).getAttribute(this.kNEST)+'em';
		}
	},
   
/* drag and drop */ 
	
	get tabbarDNDObserver() 
	{
		return this._tabbarDNDObserver || (this._tabbarDNDObserver = new TreeStyleTabBrowserTabbarDNDObserver(this));
	},
 
	get panelDNDObserver() 
	{
		return this._panelDNDObserver || (this._panelDNDObserver = new TreeStyleTabBrowserTabpanelDNDObserver(this));
	},
 
	getCurrentDragSession : function() 
	{
		return Components
				.classes['@mozilla.org/widget/dragservice;1']
				.getService(Components.interfaces.nsIDragService)
				.getCurrentSession();
	},
 
	getDropAction : function(aEvent, aDragSession) 
	{
		if (!aDragSession)
			aDragSession = this.getCurrentDragSession();

		var tab = aDragSession ? this.getTabFromChild(aDragSession.sourceNode) : null ;
		this.ensureTabInitialized(tab);

		var info = this.getDropActionInternal(aEvent, tab);
		info.canDrop = true;
		info.source = tab;
		if (tab) {
			var isCopy = this.isAccelKeyPressed(aEvent);
			if (isCopy && 'duplicateTab' in this.mTabBrowser) {
				info.action |= this.kACTION_DUPLICATE;
			}
			if (
				!isCopy &&
				this.getTabBrowserFromChild(tab) != this.mTabBrowser &&
				(
					('duplicateTab' in this.mTabBrowser) ||
					('swapBrowsersAndCloseOther' in this.mTabBrowser)
				)
				) {
				info.action |= this.kACTION_IMPORT;
			}

			if (info.action & this.kACTIONS_FOR_DESTINATION) {
				if (info.action & this.kACTION_MOVE) info.action ^= this.kACTION_MOVE;
				if (info.action & this.kACTION_STAY) info.action ^= this.kACTION_STAY;
			}

			if (info.action & this.kACTION_ATTACH) {
				if (info.parent == tab) {
					info.canDrop = false;
				}
				else {
					var orig = tab;
					tab  = info.target;
					while (tab = this.getParentTab(tab))
					{
						if (tab != orig) continue;
						info.canDrop = false;
						break;
					}
				}
			}
		}
		return info;
	},
	
	getDropActionInternal : function(aEvent, aSourceTab) 
	{
		var tab        = aEvent.target;
		var b          = this.mTabBrowser;
		var tabs       = this.getTabsArray(b);
		var lastTabIndex = tabs.length -1;
		var isInverted = this.isVertical ? false : window.getComputedStyle(b.parentNode, null).direction == 'rtl';
		var info       = {
				target       : null,
				position     : null,
				action       : null,
				parent       : null,
				insertBefore : null
			};

		var isTabMoveFromOtherWindow = aSourceTab && aSourceTab.ownerDocument != document;
		var isNewTabAction = !aSourceTab || aSourceTab.ownerDocument != document;

		if (tab.localName != 'tab') {
			var action = isTabMoveFromOtherWindow ? this.kACTION_STAY : (this.kACTION_MOVE | this.kACTION_PART) ;
			if (isNewTabAction) action |= this.kACTION_NEWTAB;
			if (aEvent[this.positionProp] < tabs[0].boxObject[this.positionProp]) {
				info.target   = info.parent = info.insertBefore = tabs[0];
				info.position = isInverted ? this.kDROP_AFTER : this.kDROP_BEFORE ;
				info.action   = action;
				return info;
			}
			else if (aEvent[this.positionProp] > tabs[lastTabIndex].boxObject[this.positionProp] + tabs[lastTabIndex].boxObject[this.sizeProp]) {
				info.target   = info.parent = tabs[lastTabIndex];
				info.position = isInverted ? this.kDROP_BEFORE : this.kDROP_AFTER ;
				info.action   = action;
				return info;
			}
			else {
				info.target = tabs[Math.min(b.getNewIndex(aEvent), lastTabIndex)];
			}
		}
		else {
			this.ensureTabInitialized(tab);
			info.target = tab;
		}

		var boxPos  = tab.boxObject[this.positionProp];
		var boxUnit = Math.round(tab.boxObject[this.sizeProp] / 3);
		if (aEvent[this.positionProp] < boxPos + boxUnit) {
			info.position = isInverted ? this.kDROP_AFTER : this.kDROP_BEFORE ;
		}
		else if (aEvent[this.positionProp] > boxPos + boxUnit + boxUnit) {
			info.position = isInverted ? this.kDROP_BEFORE : this.kDROP_AFTER ;
		}
		else {
			info.position = this.kDROP_ON;
		}

		switch (info.position)
		{
			case this.kDROP_ON:
				info.action       = this.kACTION_STAY | this.kACTION_ATTACH;
				info.parent       = tab;
				var visible = this.getNextVisibleTab(tab);
				info.insertBefore = this.getTreePref('insertNewChildAt') == this.kINSERT_FISRT ?
						(this.getFirstChildTab(tab) || visible) :
						(this.getNextSiblingTab(tab) || this.getNextTab(this.getLastDescendantTab(tab)) || visible);
				break;

			case this.kDROP_BEFORE:
/*
	[TARGET  ] ↑part from parent, and move

	  [      ]
	[TARGET  ] ↑attach to the parent of the target, and move

	[        ]
	[TARGET  ] ↑attach to the parent of the target, and move

	[        ]
	  [TARGET] ↑attach to the parent of the target (previous tab), and move
*/
				var prevTab = this.getPreviousVisibleTab(tab);
				if (!prevTab) {
					info.action       = this.kACTION_MOVE | this.kACTION_PART;
					info.insertBefore = tabs[0];
				}
				else {
					var prevLevel   = Number(prevTab.getAttribute(this.kNEST));
					var targetNest = Number(tab.getAttribute(this.kNEST));
					info.parent       = (prevLevel < targetNest) ? prevTab : this.getParentTab(tab) ;
					info.action       = this.kACTION_MOVE | (info.parent ? this.kACTION_ATTACH : this.kACTION_PART );
					info.insertBefore = tab;
				}
				break;

			case this.kDROP_AFTER:
/*
	[TARGET  ] ↓if the target has a parent, attach to it and and move

	  [TARGET] ↓attach to the parent of the target, and move
	[        ]

	[TARGET  ] ↓attach to the parent of the target, and move
	[        ]

	[TARGET  ] ↓attach to the target, and move
	  [      ]
*/
				var nextTab = this.getNextVisibleTab(tab);
				if (!nextTab) {
					info.action = this.kACTION_MOVE | this.kACTION_ATTACH;
					info.parent = this.getParentTab(tab);
				}
				else {
					var targetNest = Number(tab.getAttribute(this.kNEST));
					var nextLevel   = Number(nextTab.getAttribute(this.kNEST));
					info.parent       = (targetNest < nextLevel) ? tab : this.getParentTab(tab) ;
					info.action       = this.kACTION_MOVE | (info.parent ? this.kACTION_ATTACH : this.kACTION_PART );
					info.insertBefore = nextTab;
/*
	[TARGET   ] ↓attach dragged tab to the parent of the target as its next sibling
	  [DRAGGED]
*/
					if (aSourceTab == nextTab && this.getDescendantTabs(info.parent).length == 1) {
						info.action = this.kACTION_MOVE | this.kACTION_ATTACH;
						info.parent = this.getParentTab(tab);
						info.insertBefore = this.getNextTab(nextTab);
					}
				}
				break;
		}

		if (isNewTabAction) action |= this.kACTION_NEWTAB;

		return info;
	},
  
	performDrop : function(aInfo, aDraggedTab) 
	{
		var tabsInfo = this.getDraggedTabsInfoFromOneTab(aInfo, aDraggedTab);
		aDraggedTab = tabsInfo.draggedTab;
		var draggedTabs = tabsInfo.draggedTabs;
		var draggedRoots = tabsInfo.draggedRoots;

		var targetBrowser = this.mTabBrowser;
		var tabs = this.getTabsArray(targetBrowser);

		var sourceWindow = aDraggedTab.ownerDocument.defaultView;
		var sourceBrowser = this.getTabBrowserFromChild(aDraggedTab);

		var draggedWholeTree = [].concat(draggedRoots);
		draggedRoots.forEach(function(aRoot) {
			draggedWholeTree = draggedWholeTree.concat(this.getDescendantTabs(aRoot));
		}, this);
		while (aInfo.insertBefore && draggedWholeTree.indexOf(aInfo.insertBefore) > -1)
		{
			aInfo.insertBefore = this.getNextTab(aInfo.insertBefore);
		}

		if (aInfo.action & this.kACTIONS_FOR_SOURCE) {
			if (aInfo.action & this.kACTION_PART) {
				this.partTabsOnDrop(draggedRoots);
			}
			else if (aInfo.action & this.kACTION_ATTACH) {
				this.attachTabsOnDrop(draggedRoots, aInfo.parent);
			}
			else {
				return false;
			}

			if ( // if this move will cause no change...
				sourceBrowser == targetBrowser &&
				sourceBrowser.treeStyleTab.getNextVisibleTab(draggedTabs[draggedTabs.length-1]) == aInfo.insertBefore
				) {
				// then, do nothing
				return true;
			}
		}


		// prevent Multiple Tab Handler feature
		targetBrowser.duplicatingSelectedTabs = true;
		targetBrowser.movingSelectedTabs = true;


		var newRoots = [];
		var shouldClose = (
				aInfo.action & this.kACTION_IMPORT &&
				this.getTabs(sourceBrowser).snapshotLength == draggedTabs.length
			);
		var oldTabs = [];
		var newTabs = [];
		var treeStructure = draggedTabs.map(function(aTab) {
				var parent = sourceBrowser.treeStyleTab.getParentTab(aTab);
				return parent ? draggedTabs.indexOf(parent) : -1 ;
			});

		var parentTabsArray = draggedTabs.map(function(aTab) {
				return (aInfo.action & this.kACTIONS_FOR_DESTINATION) ?
					sourceBrowser.treeStyleTab.getParentTab(aTab) : null ;
			}, this);

		// Firefox fails to "move" collapsed tabs. So, expand them first
		// and collapse them after they are moved.
		var collapseExpandState = [];
		if (aInfo.action & this.kACTION_IMPORT &&
			'swapBrowsersAndCloseOther' in targetBrowser) {
			draggedWholeTree.forEach(function(aTab) {
				collapseExpandState.push(this.getTabValue(aTab, this.kSUBTREE_COLLAPSED) == 'true');
				this.collapseExpandSubtree(aTab, false, true);
				this.collapseExpandTab(aTab, false, true);
			}, this);
		}

		var lastTabIndex = tabs.length -1;
		draggedTabs.forEach(function(aTab, aIndex) {
			var tab = aTab;
			if (aInfo.action & this.kACTIONS_FOR_DESTINATION) {
				var parent = parentTabsArray[aIndex];
				if (tabsInfo.isSelectionMove)
					sourceWindow.MultipleTabService.setSelection(aTab, false);
				if (aInfo.action & this.kACTION_IMPORT &&
					'swapBrowsersAndCloseOther' in targetBrowser) {
					tab = targetBrowser.addTab();
					tab.linkedBrowser.stop();
					tab.linkedBrowser.docShell;
					targetBrowser.swapBrowsersAndCloseOther(tab, aTab);
					targetBrowser.setTabTitle(tab);
				}
				else {
					tab = targetBrowser.duplicateTab(aTab);
					this.deleteTabValue(tab, this.kCHILDREN);
					this.deleteTabValue(tab, this.kPARENT);
					if (aInfo.action & this.kACTION_IMPORT)
						oldTabs.push(aTab);
				}
				newTabs.push(tab);
				if (tabsInfo.isSelectionMove)
					MultipleTabService.setSelection(tab, true);
				if (!parent || draggedTabs.indexOf(parent) < 0)
					newRoots.push(tab);
				lastTabIndex++;
			}

			var newIndex = aInfo.insertBefore ? aInfo.insertBefore._tPos : lastTabIndex ;
			if (aInfo.insertBefore && newIndex > tab._tPos) newIndex--;

			this.internallyTabMoving = true;
			targetBrowser.moveTabTo(tab, newIndex);
			this.collapseExpandTab(tab, false, true);
			this.internallyTabMoving = false;

		}, this);

		// close imported tabs from the source browser
		oldTabs.forEach(function(aTab) {
			sourceBrowser.removeTab(aTab);
		});
		if (shouldClose) this.closeOwner(sourceBrowser);

		// restore tree structure for newly opened tabs
		newTabs.forEach(function(aTab, aIndex) {
			var index = treeStructure[aIndex];
			if (index < 0) return;
			targetBrowser.treeStyleTab.attachTabTo(aTab, newTabs[index]);
		});
		newTabs.reverse();
		collapseExpandState.reverse();
		collapseExpandState.forEach(function(aCollapsed, aIndex) {
			this.collapseExpandSubtree(newTabs[aIndex], aCollapsed, true);
		}, this);

		if (aInfo.action & this.kACTIONS_FOR_DESTINATION &&
			aInfo.action & this.kACTION_ATTACH)
			this.attachTabsOnDrop(newRoots, aInfo.parent);

		// Multiple Tab Handler
		targetBrowser.movingSelectedTabs = false;
		targetBrowser.duplicatingSelectedTabs = false;

		return true;
	},
	
	getDraggedTabsInfoFromOneTab : function(aInfo, aTab) 
	{
		aTab = this.getTabFromChild(aTab);

		var targetBrowser = this.mTabBrowser;
		var tabs = this.getTabsArray(targetBrowser);

		var draggedTabs = [aTab];
		var draggedRoots = [aTab];

		var sourceWindow = aTab.ownerDocument.defaultView;
		var sourceBrowser = this.getTabBrowserFromChild(aTab);


		var isSelectionMove = (
				'MultipleTabService' in sourceWindow &&
				sourceWindow.MultipleTabService.isSelected(aTab) &&
				MultipleTabService.allowMoveMultipleTabs
			);

		if (isSelectionMove) {
			draggedTabs = sourceWindow.MultipleTabService.getSelectedTabs(sourceBrowser);
			if (!(aInfo.action & this.kACTIONS_FOR_DESTINATION)) {
				draggedRoots = [];
				draggedTabs.forEach(function(aTab) {
					var parent = aTab,
						current;
					do {
						current = parent;
						parent = sourceBrowser.treeStyleTab.getParentTab(parent)
						if (parent && sourceWindow.MultipleTabService.isSelected(parent)) continue;
						draggedRoots.push(current);
						return;
					}
					while (parent);
				}, this);
			}
		}
		else if (aInfo.action & this.kACTIONS_FOR_DESTINATION) {
			draggedTabs = draggedTabs.concat(sourceBrowser.treeStyleTab.getDescendantTabs(aTab));
		}

		return {
			draggedTab      : aTab,
			draggedTabs     : draggedTabs,
			draggedRoots    : draggedRoots,
			isSelectionMove : isSelectionMove
		};
	},
 
	attachTabsOnDrop : function(aTabs, aParent) 
	{
		this.mTabBrowser.movingSelectedTabs = true; // Multiple Tab Handler
		aTabs.forEach(function(aTab) {
			if (!aTab.parentNode) return; // ignore removed tabs
			if (aParent)
				this.attachTabTo(aTab, aParent);
			else
				this.partTab(aTab);
			this.collapseExpandTab(aTab, false);
		}, this);
		this.mTabBrowser.movingSelectedTabs = false; // Multiple Tab Handler
	},
 
	partTabsOnDrop : function(aTabs) 
	{
		this.mTabBrowser.movingSelectedTabs = true; // Multiple Tab Handler
		aTabs.forEach(function(aTab) {
			if (!aTab.parentNode) return; // ignore removed tabs
			this.partTab(aTab);
			this.collapseExpandTab(aTab, false);
		}, this);
		this.mTabBrowser.movingSelectedTabs = false; // Multiple Tab Handler
	},
 
	closeOwner : function(aTabOwner) 
	{
		var w = aTabOwner.ownerDocument.defaultView;
		if (!w) return;
		if ('SplitBrowser' in w) {
			if ('getSubBrowserFromChild' in w.SplitBrowser) {
				var subbrowser = w.SplitBrowser.getSubBrowserFromChild(aTabOwner);
				if (subbrowser) {
					subbrowser.close();
					return;
				}
			}
			if (w.SplitBrowser.browsers.length) return;
		}
		w.close();
	},
  
	clearDropPosition : function() 
	{
		var b = this.mTabBrowser;
		var xpathResult = this.evaluateXPath(
				'child::xul:tab[@'+this.kDROP_POSITION+']',
				b.mTabContainer
			);
		for (var i = 0, maxi = xpathResult.snapshotLength; i < maxi; i++)
		{
			xpathResult.snapshotItem(i).removeAttribute(this.kDROP_POSITION);
		}
	},
 
	isDraggingAllTabs : function(aTab) 
	{
		var actionInfo = {
				action : this.kACTIONS_FOR_DESTINATION | this.kACTION_IMPORT
			};
		var tabsInfo = this.getDraggedTabsInfoFromOneTab(actionInfo, aTab);
		return tabsInfo.draggedTabs.length == this.getTabs(this.mTabBrowser).snapshotLength;
	},
  
/* commands */ 
	
/* attach/part */ 
	
	attachTabTo : function(aChild, aParent, aInfo) /* PUBLIC API */ 
	{
		var currentParent;
		if (
			!aChild ||
			!aParent ||
			aChild == aParent ||
			(currentParent = this.getParentTab(aChild)) == aParent
			) {
			/* PUBLIC API */
			let event = document.createEvent('Events');
			event.initEvent('TreeStyleTabAttached', true, true);
			event.parentTab = aParent;
			aChild.dispatchEvent(event);
			return;
		}

		shouldInheritIndent = (
			!currentParent ||
			(currentParent.getAttribute(this.kNEST) == aParent.getAttribute(this.kNEST))
		);

		this.ensureTabInitialized(aChild);
		this.ensureTabInitialized(aParent);

		if (!aInfo) aInfo = {};

		var id = aChild.getAttribute(this.kID);

		this.partTab(aChild, {
			dontUpdateIndent : true
		});

		var children = aParent.getAttribute(this.kCHILDREN)
						.split('|').filter(function(aId) {
							return this.getTabById(aId);
						}, this);

		var newIndex;

		var oldIndex = children.indexOf(id);
		if (oldIndex > -1) children.splice(oldIndex, 1);

		var insertBefore = aInfo.insertBefore ||
						(aInfo.dontMove ? this.getNextTab(aChild) : null );
		var beforeTab = insertBefore ? insertBefore.getAttribute(this.kID) : null ;
		var beforeIndex;
		if (beforeTab && (beforeIndex = children.indexOf(beforeTab)) > -1) {
			children.splice(beforeIndex, 0, id);
			newIndex = insertBefore._tPos;
		}
		else {
			children.push(id);
			let refTab = aParent;
			let descendant = this.getDescendantTabs(aParent);
			if (descendant.length) refTab = descendant[descendant.length-1];
			newIndex = refTab._tPos+1;
		}

		this.setTabValue(aParent, this.kCHILDREN, children.join('|'));
		this.setTabValue(aChild, this.kPARENT, aParent.getAttribute(this.kID));
		this.updateTabsCount(aParent);
		if (shouldInheritIndent && !aInfo.dontUpdateIndent)
			this.inheritTabIndent(aChild, aParent);

		if (!aInfo.dontMove) {
			if (newIndex > aChild._tPos) newIndex--;
			this.moveTabSubTreeTo(aChild, newIndex);
		}

		if (!aInfo.dontExpand) {
			if (this.getTreePref('autoCollapseExpandSubTreeOnSelect')) {
				this.collapseExpandTreesIntelligentlyFor(aParent);
				var p = aParent;
				do {
					this.collapseExpandSubtree(p, false, aInfo.dontAnimate);
				}
				while (p = this.getParentTab(p));
			}
			else if (aParent.getAttribute(this.kSUBTREE_COLLAPSED) == 'true') {
				if (this.getTreePref('autoExpandSubTreeOnAppendChild')) {
					var p = aParent;
					do {
						this.collapseExpandSubtree(p, false, aInfo.dontAnimate);
					}
					while (p = this.getParentTab(p));
				}
				else
					this.collapseExpandTab(aChild, true, aInfo.dontAnimate);
			}

			if (aParent.getAttribute(this.kCOLLAPSED) == 'true')
				this.collapseExpandTab(aChild, true, aInfo.dontAnimate);
		}
		else if (aParent.getAttribute(this.kSUBTREE_COLLAPSED) == 'true' ||
				aParent.getAttribute(this.kCOLLAPSED) == 'true') {
			this.collapseExpandTab(aChild, true, aInfo.dontAnimate);
		}

		if (!aInfo.dontUpdateIndent) {
			this.updateTabsIndent([aChild], undefined, undefined, aInfo.dontAnimate);
			this.checkTabsIndentOverflow();
		}

		/* PUBLIC API */
		var event = document.createEvent('Events');
		event.initEvent('TreeStyleTabAttached', true, true);
		event.parentTab = aParent;
		aChild.dispatchEvent(event);
	},
 
	partTab : function(aChild, aInfo) /* PUBLIC API */ 
	{
		if (!aChild) return;
		if (!aInfo) aInfo = {};

		var parentTab = this.getParentTab(aChild);
		if (!parentTab) return;

		var id = aChild.getAttribute(this.kID);
		this.setTabValue(
			parentTab,
			this.kCHILDREN,
			parentTab.getAttribute(this.kCHILDREN)
				.split('|')
				.filter(function(aId) {
					return this.getTabById(aId) && aId != id;
				}, this).join('|')
		);
		this.deleteTabValue(aChild, this.kPARENT);
		this.updateTabsCount(parentTab);

		if (!aInfo.dontUpdateIndent) {
			this.updateTabsIndent([aChild], undefined, undefined, aInfo.dontAnimate);
			this.checkTabsIndentOverflow();
		}

		/* PUBLIC API */
		var event = document.createEvent('Events');
		event.initEvent('TreeStyleTabParted', true, true);
		aChild.dispatchEvent(event);

		if (this.isGroupTab(parentTab) && !this.hasChildTabs(parentTab)) {
			window.setTimeout(function(aTabBrowser) {
				if (parentTab.parentNode)
					aTabBrowser.removeTab(parentTab);
				parentTab = null;
			}, 0, this.getTabBrowserFromChild(parentTab));
		}
	},
	detachTab : function(aChild, aInfo) // alias (unstable API!)
	{
		return this.partTab(aChild, aInfo);
	},
 
	updateTabsIndent : function(aTabs, aLevel, aProp, aJustNow) 
	{
		if (!aTabs || !aTabs.length) return;

		if (aLevel === void(0)) {
			var parentTab = this.getParentTab(aTabs[0]);
			var aLevel = 0;
			while (parentTab)
			{
				aLevel++;
				parentTab = this.getParentTab(parentTab);
			}
		}

		var b = this.mTabBrowser;
		if (!aProp) {
			let orient = this.isVertical ? 'vertical' : 'horizontal' ;
			aProp = this.getTreePref('enableSubtreeIndent.'+orient) ? this.indentProp : null ;
		}
		var margin = this.indent < 0 ? this.baseIndent : this.indent ;
		var indent = margin * aLevel;

		var multirow = this.isMultiRow();
		var topBottom = this.indentProp.match(/top|bottom/);
		var maxIndent = parseInt(aTabs[0].boxObject.height / 2);

		Array.slice(aTabs).forEach(function(aTab) {
			if (!aTab.parentNode) return; // ignore removed tabs
			if (multirow) {
				indent = Math.min(aLevel * 3, maxIndent);
				var colors = '-moz-border-'+topBottom+'-colors:'+(function(aNum) {
					var retVal = [];
					for (var i = 1; i < aNum; i++)
					{
						retVal.push('transparent');
					}
					retVal.push('ThreeDShadow');
					return retVal.length == 1 ? 'none' : retVal.join(' ') ;
				})(indent)+' !important;';
				Array.slice(document.getAnonymousNodes(aTab)).forEach(function(aBox) {
					if (aBox.nodeType != Node.ELEMENT_NODE) return;
					aBox.setAttribute(
						'style',
						aBox.getAttribute('style').replace(/(-moz-)?border-(top|bottom)(-[^:]*)?.*:[^;]+;?/g, '') +
						'; border-'+topBottom+': solid transparent '+indent+'px !important;'+colors
					);
				}, this);
			}
			else {
				this.updateTabIndent(aTab, aProp, indent, aJustNow);
			}
			aTab.setAttribute(this.kNEST, aLevel);
			this.updateTabsIndent(this.getChildTabs(aTab), aLevel+1, aProp, aJustNow);
		}, this);
	},
	updateTabsIndentWithDelay : function(aTabs)
	{
		if (this.updateTabsIndentWithDelayTimer)
			window.clearTimeout(this.updateTabsIndentWithDelayTimer);

		this.updateTabsIndentWithDelayTabs = this.updateTabsIndentWithDelayTabs.concat(aTabs);
		this.updateTabsIndentWithDelayTimer = window.setTimeout(function(aSelf) {
			var tabs = [];
			aSelf.updateTabsIndentWithDelayTabs.forEach(function(aTab) {
				if (tabs.indexOf(aTab) < 0 && aTab.parentNode) tabs.push(aTab);
			});
			aSelf.updateTabsIndentWithDelayTabs = [];
			aSelf.updateTabsIndent(tabs);
			window.clearTimeout(aSelf.updateTabsIndentWithDelayTimer);
			aSelf.updateTabsIndentWithDelayTimer = null;
			tabs = null;
		}, 0, this);
	},
	updateTabsIndentWithDelayTabs : [],
	updateTabsIndentWithDelayTimer : null,
 
	updateTabIndent : function(aTab, aProp, aIndent, aJustNow) 
	{
		this.stopTabIndentAnimation(aTab);

		var regexp = this.indentRulesRegExp;
		if (
			!this.animationEnabled ||
			aJustNow ||
			this.indentDuration < 1 ||
			!aProp ||
			(aTab.getAttribute(this.kCOLLAPSED) == 'true')
			) {
			aTab.setAttribute(
				'style',
				aTab.getAttribute('style')
					.replace(regexp, '')+';'+
					(aProp ? aProp+':'+aIndent+'px !important;' : '' )
			);
			return;
		}

		var startIndent = this.getPropertyPixelValue(aTab, aProp);
		var delta       = aIndent - startIndent;
		var radian      = 90 * Math.PI / 180;
		var self        = this;
		aTab.__treestyletab__updateTabIndentTask = function(aTime, aBeginning, aChange, aDuration) {
			var indent, finished;
			if (aTime >= aDuration) {
				delete aTab.__treestyletab__updateTabIndentTask;
				indent = aIndent;
				finished = true;
			}
			else {
				indent = startIndent + (delta * Math.sin(aTime / aDuration * radian));
				finished = false;
			}
			aTab.setAttribute(
				'style',
				aTab.getAttribute('style').replace(regexp, '')+';'+
				aProp+':'+indent+'px !important;'
			);
			if (finished) {
				startIndent = null;
				delta = null;
				radian = null;
				self = null;
				aTab = null;
			}
			return finished;
		};
		window['piro.sakura.ne.jp'].animationManager.addTask(
			aTab.__treestyletab__updateTabIndentTask,
			0, 0, this.indentDuration
		);
	},
	stopTabIndentAnimation : function(aTab)
	{
		window['piro.sakura.ne.jp'].animationManager.removeTask(
			aTab.__treestyletab__updateTabIndentTask
		);
	},
 
	inheritTabIndent : function(aNewTab, aExistingTab) 
	{
		var regexp = this.indentRulesRegExp;
		var indents = (aExistingTab.getAttribute('style') || '').match(regexp) || [];
		aNewTab.setAttribute(
			'style',
			aNewTab.getAttribute('style')
				.replace(regexp, '')+';'+indents.join(';')
		);
	},
 
	updateAllTabsIndent : function() 
	{
		this.updateTabsIndent(this.rootTabs, 0);
//		this.checkTabsIndentOverflow();
	},
 
	checkTabsIndentOverflow : function() 
	{
		if (this.checkTabsIndentOverflowTimer) {
			window.clearTimeout(this.checkTabsIndentOverflowTimer);
			this.checkTabsIndentOverflowTimer = null;
		}
		this.checkTabsIndentOverflowTimer = window.setTimeout(function(aSelf) {
			aSelf.checkTabsIndentOverflowCallback();
		}, 100, this);
	},
	checkTabsIndentOverflowTimer : null,
	checkTabsIndentOverflowCallback : function()
	{
		var b    = this.mTabBrowser;
		var tabs = this.getArrayFromXPathResult(this.evaluateXPath(
				'child::xul:tab[@'+this.kNEST+' and not(@'+this.kNEST+'="0" or @'+this.kNEST+'="")]',
				b.mTabContainer
			));
		if (!tabs.length) return;

		var self = this;
		tabs.sort(function(aA, aB) { return Number(aA.getAttribute(self.kNEST)) - Number(aB.getAttribute(self.kNEST)); });
		var nest = tabs[tabs.length-1].getAttribute(this.kNEST);
		if (!nest) return;

		var oldIndent = this.indent;
		var indent    = (oldIndent < 0 ? this.baseIndent : oldIndent ) * nest;
		var maxIndentBase = Math.min(
					this.getFirstTab(b).boxObject[this.invertedSizeProp],
					b.mTabContainer.boxObject[this.invertedSizeProp]
				);
		if (!this.isVertical) {
			if (this._horizontalTabMaxIndentBase)
				maxIndentBase = this._horizontalTabMaxIndentBase;
			else
				this._horizontalTabMaxIndentBase = maxIndentBase;
		}
		var maxIndent = maxIndentBase * (this.isVertical ? 0.33 : 0.5 );

		var indentUnit = Math.max(Math.floor(maxIndent / nest), 1);
		if (indent > maxIndent) {
			this.indent = indentUnit;
		}
		else {
			this.indent = -1;
			if ((this.baseIndent * nest) > maxIndent)
				this.indent = indentUnit;
		}

		if (oldIndent != this.indent) {
			this.updateAllTabsIndent();
		}
	},
	_horizontalTabMaxIndentBase : 0,
 
	updateTabsCount : function(aTab, aDontUpdateAncestor) 
	{
		var count = document.getAnonymousElementByAttribute(aTab, 'class', this.kCOUNTER);
		if (count) {
			count.setAttribute('value', '('+this.getDescendantTabs(aTab).length+')');
		}
		var parent = this.getParentTab(aTab);
		if (parent && !aDontUpdateAncestor)
			this.updateTabsCount(parent);
	},
  
/* move */ 
	
	moveTabSubTreeTo : function(aTab, aIndex) 
	{
		if (!aTab) return;

		var b = this.mTabBrowser;
		this.isSubTreeMoving = true;

		this.internallyTabMoving = true;
		b.moveTabTo(aTab, aIndex);
		this.internallyTabMoving = false;

		this.isSubTreeChildrenMoving = true;
		this.internallyTabMoving     = true;
		this.getDescendantTabs(aTab).forEach(function(aDescendantTab, aIndex) {
			b.moveTabTo(aDescendantTab, aTab._tPos + aIndex + (aTab._tPos < aDescendantTab._tPos ? 1 : 0 ));
		}, this);
		this.internallyTabMoving     = false;
		this.isSubTreeChildrenMoving = false;

		this.isSubTreeMoving = false;
	},
 
	moveTabLevel : function(aEvent) 
	{
		var b = this.mTabBrowser;
		var parentTab = this.getParentTab(b.mCurrentTab);
		if (aEvent.keyCode == KeyEvent.DOM_VK_RIGHT) {
			var prevTab = this.getPreviousSiblingTab(b.mCurrentTab);
			if ((!parentTab && prevTab) ||
				(parentTab && b.mCurrentTab != this.getFirstChildTab(parentTab))) {
				this.attachTabTo(b.mCurrentTab, prevTab);
				b.mCurrentTab.focus();
				return true;
			}
		}
		else if (aEvent.keyCode == KeyEvent.DOM_VK_LEFT && parentTab) {
			var grandParent = this.getParentTab(parentTab);
			if (grandParent) {
				this.attachTabTo(b.mCurrentTab, grandParent, {
					insertBefore : this.getNextSiblingTab(parentTab)
				});
				b.mCurrentTab.focus();
				return true;
			}
			else {
				var nextTab = this.getNextSiblingTab(parentTab);
				this.partTab(b.mCurrentTab);
				this.internallyTabMoving = true;
				if (nextTab) {
					b.moveTabTo(b.mCurrentTab, nextTab._tPos - 1);
				}
				else {
					b.moveTabTo(b.mCurrentTab, this.getLastTab(b)._tPos);
				}
				this.internallyTabMoving = false;
				b.mCurrentTab.focus();
				return true;
			}
		}
		return false;
	},
  
/* collapse/expand */ 
	
	collapseExpandSubtree : function(aTab, aCollapse, aJustNow) /* PUBLIC API */ 
	{
		if (!aTab) return;

		if ((aTab.getAttribute(this.kSUBTREE_COLLAPSED) == 'true') == aCollapse) return;

		var b = this.mTabBrowser;
		this.doingCollapseExpand = true;

		this.setTabValue(aTab, this.kSUBTREE_COLLAPSED, aCollapse);

		this.getChildTabs(aTab).forEach(function(aTab) {
			this.collapseExpandTab(aTab, aCollapse, aJustNow);
		}, this);

		if (!aCollapse)
			this.scrollToTabSubTree(aTab);

		this.doingCollapseExpand = false;
	},
 
	collapseExpandTab : function(aTab, aCollapse, aJustNow) 
	{
		if (!aTab || !this.getParentTab(aTab)) return;

		this.setTabValue(aTab, this.kCOLLAPSED, aCollapse);
		this.updateTabCollapsed(aTab, aCollapse, aJustNow);

		/* PUBLIC API */
		var event = document.createEvent('Events');
		event.initEvent('TreeStyleTabCollapsedStateChange', true, true);
		event.collapsed = aCollapse;
		aTab.dispatchEvent(event);

		var b = this.mTabBrowser;
		var parent;
		if (aCollapse && aTab == b.selectedTab && (parent = this.getParentTab(aTab))) {
			var newSelection = parent;
			while (parent.getAttribute(this.kCOLLAPSED) == 'true')
			{
				parent = this.getParentTab(parent);
				if (!parent) break;
				newSelection = parent;
			}
			b.selectedTab = newSelection;
		}

		if (aTab.getAttribute(this.kSUBTREE_COLLAPSED) != 'true') {
			this.getChildTabs(aTab).forEach(function(aTab) {
				this.collapseExpandTab(aTab, aCollapse, aJustNow);
			}, this);
		}
	},
	updateTabCollapsed : function(aTab, aCollapsed, aJustNow)
	{
		this.stopTabCollapseAnimation(aTab);

		aTab.removeAttribute(this.kX_OFFSET);
		aTab.removeAttribute(this.kY_OFFSET);

		if (
			!this.animationEnabled ||
			aJustNow ||
			this.collapseDuration < 1 ||
//			!this.isVertical ||
			this.mTabBrowser.getAttribute(this.kALLOW_COLLAPSE) != 'true'
			) {
			aTab.setAttribute(
				'style',
				aTab.getAttribute('style')
					.replace(this.collapseRulesRegExp, '')
					.replace(this.kOPACITY_RULE_REGEXP, '')
			);
			aTab.removeAttribute(this.kCOLLAPSING);
			if (aCollapsed)
				aTab.setAttribute(this.kCOLLAPSED_DONE, true);
			else
				aTab.removeAttribute(this.kCOLLAPSED_DONE);
			return;
		}

		var maxMargin;
		var offsetAttr;
		let (firstTab) {
			firstTab = this.getFirstTab(this.mTabBrowser);
			if (this.isVertical) {
				maxMargin = firstTab.boxObject.height;
				offsetAttr = this.kY_OFFSET;
				if (firstTab.style.height)
					aTab.style.height = firstTab.style.height;
			}
			else {
				maxMargin = firstTab.boxObject.width;
				offsetAttr = this.kX_OFFSET;
				if (firstTab.style.width)
					aTab.style.width = firstTab.style.width;
			}
		}

		var startMargin, endMargin, startOpacity, endOpacity;
		if (aCollapsed) {
			startMargin  = 0;
			endMargin    = maxMargin;
			startOpacity = 1;
			endOpacity   = 0;
		}
		else {
			aTab.setAttribute(offsetAttr, maxMargin);
			startMargin  = maxMargin;
			endMargin    = 0;
			startOpacity = 0;
			endOpacity   = 1;
		}
		var deltaMargin  = endMargin - startMargin;
		var deltaOpacity = endOpacity - startOpacity;
		var collapseProp = this.collapseProp;

		aTab.setAttribute(this.kCOLLAPSING, true);
		aTab.setAttribute(
			'style',
			aTab.getAttribute('style')
				.replace(this.collapseRulesRegExp, '')+';'+
				collapseProp+': -'+startMargin+'px !important;'+
				'opacity: '+startOpacity+' !important;'
		);

		if (!aCollapsed) aTab.removeAttribute(this.kCOLLAPSED_DONE);

		var radian = 90 * Math.PI / 180;
		var self   = this;
		aTab.__treestyletab__updateTabCollapsedTask = function(aTime, aBeginning, aChange, aDuration) {
			// If this is the last tab, negative scroll happens.
			// Then, we shouldn't do animation.
			var stopAnimation = false;
			var scrollBox = self.scrollBox;
			if (scrollBox) {
				if (scrollBox._scrollbox) scrollBox = scrollBox._scrollbox;
				if ('scrollTop' in scrollBox &&
					(scrollBox.scrollTop < 0 || scrollBox.scrollLeft < 0)) {
					scrollBox.scrollTop = 0;
					scrollBox.scrollLeft = 0;
					stopAnimation = true;
				}
			}
			if (aTime >= aDuration || stopAnimation) {
				delete aTab.__treestyletab__updateTabCollapsedTask;
				aTab.removeAttribute(self.kCOLLAPSING);
				if (aCollapsed) aTab.setAttribute(self.kCOLLAPSED_DONE, true);
				aTab.setAttribute(
					'style',
					aTab.getAttribute('style')
						.replace(self.collapseRulesRegExp, '')
						.replace(self.kOPACITY_RULE_REGEXP, '')
				);
				aTab.removeAttribute(offsetAttr);

				maxMargin = null;
				offsetAttr = null;
				startMargin = null;
				endMargin = null;
				startOpacity = null;
				endOpacity = null;
				deltaMargin = null;
				deltaOpacity = null;
				collapseProp = null;
				radian = null;
				self = null;
				aTab = null;

				return true;
			}
			else {
				var power   = Math.sin(aTime / aDuration * radian);
				var margin  = startMargin + (deltaMargin * power);
				var opacity = startOpacity + (deltaOpacity  * power);
				aTab.setAttribute(
					'style',
					aTab.getAttribute('style')
						.replace(self.collapseRulesRegExp, '')+';'+
						collapseProp+': -'+margin+'px !important;'+
						'opacity: '+opacity+' !important;'
				);
				aTab.setAttribute(offsetAttr, maxMargin);
				return false;
			}
		};
		window['piro.sakura.ne.jp'].animationManager.addTask(
			aTab.__treestyletab__updateTabCollapsedTask,
			0, 0, this.collapseDuration
		);
	},
	kOPACITY_RULE_REGEXP : /opacity\s*:[^;]+;?/,
	stopTabCollapseAnimation : function(aTab)
	{
		window['piro.sakura.ne.jp'].animationManager.removeTask(
			aTab.__treestyletab__updateTabCollapsedTask
		);
	},
 
	collapseExpandTreesIntelligentlyFor : function(aTab, aJustNow) 
	{
		if (!aTab || this.doingCollapseExpand) return;

		var b = this.mTabBrowser;
		var sameParentTab = this.getParentTab(aTab);
		var expandedParentTabs = [
				aTab.getAttribute(this.kID)
			];
		var parentTab = aTab;
		while (parentTab = this.getParentTab(parentTab))
		{
			expandedParentTabs.push(parentTab.getAttribute(this.kID));
		}
		expandedParentTabs = expandedParentTabs.join('|');

		var xpathResult = this.evaluateXPath(
				'child::xul:tab[@'+this.kCHILDREN+' and not(@'+this.kCOLLAPSED+'="true") and not(@'+this.kSUBTREE_COLLAPSED+'="true") and @'+this.kID+' and not(contains("'+expandedParentTabs+'", @'+this.kID+'))]',
				b.mTabContainer
			);
		var collapseTab;
		var dontCollapse;
		for (var i = 0, maxi = xpathResult.snapshotLength; i < maxi; i++)
		{
			dontCollapse = false;
			collapseTab  = xpathResult.snapshotItem(i);

			parentTab = this.getParentTab(collapseTab);
			if (parentTab) {
				dontCollapse = true;
				if (parentTab.getAttribute(this.kSUBTREE_COLLAPSED) != 'true') {
					do {
						if (expandedParentTabs.indexOf(parentTab.getAttribute(this.kID)) < 0)
							continue;
						dontCollapse = false;
						break;
					}
					while (parentTab = this.getParentTab(parentTab));
				}
			}

			if (!dontCollapse)
				this.collapseExpandSubtree(collapseTab, true, aJustNow);
		}

		this.collapseExpandSubtree(aTab, false, aJustNow);
	},
	collapseExpandTreesIntelligentlyWithDelayFor : function(aTab)
	{
		if (this.doingCollapseExpand) return;
		if (this.cETIWDFTimer)
			window.clearTimeout(this.cETIWDFTimer);
		this.cETIWDFTimer = window.setTimeout(function(aSelf) {
			window.clearTimeout(aSelf.cETIWDFTimer);
			aSelf.cETIWDFTimer = null;
			aSelf.collapseExpandTreesIntelligentlyFor(aTab);
		}, 0, this);
	},
	cETIWDFTimer : null,
 
	collapseExpandAllSubtree : function(aCollapse, aJustNow) 
	{
		var xpathResult = this.evaluateXPath(
				'child::xul:tab[@'+this.kID+' and @'+this.kCHILDREN+
				(
					aCollapse ?
						' and not(@'+this.kSUBTREE_COLLAPSED+'="true")' :
						' and @'+this.kSUBTREE_COLLAPSED+'="true"'
				)+
				']',
				this.mTabBrowser.mTabContainer
			);
		for (var i = 0, maxi = xpathResult.snapshotLength; i < maxi; i++)
		{
			this.collapseExpandSubtree(xpathResult.snapshotItem(i), aCollapse, aJustNow);
		}
	},
  
/* scroll */ 
	
	scrollTo : function(aEndX, aEndY) 
	{
		if (this.animationEnabled || this.smoothScrollEnabled) {
			this.smoothScrollTo(aEndX, aEndY);
		}
		else {
			try {
				this.scrollBoxObject.scrollTo(aEndX, aEndY);
			}
			catch(e) {
			}
		}
	},
	
	smoothScrollTo : function(aEndX, aEndY) 
	{
		var b = this.mTabBrowser;
		window['piro.sakura.ne.jp'].animationManager.removeTask(this.smoothScrollTask);

		var scrollBoxObject = this.scrollBoxObject;
		var x = {}, y = {};
		scrollBoxObject.getPosition(x, y);
		var startX = x.value;
		var startY = y.value;
		var deltaX = aEndX - startX;
		var deltaY = aEndY - startY;

		var radian = 90 * Math.PI / 180;
		var self = this;
		this.smoothScrollTask = function(aTime, aBeginning, aChange, aDuration) {
			var scrollBoxObject = self.scrollBoxObject;
			if (aTime >= aDuration) {
				scrollBoxObject.scrollTo(aEndX, aEndY);

				b = null;
				scrollBoxObject = null;
				x = null;
				y = null;
				startX = null;
				startY = null;
				radian = null;
				self = null;

				return true;
			}

			var power = Math.sin(aTime / aDuration * radian);
			var newX = startX + parseInt(deltaX * power);
			var newY = startY + parseInt(deltaY * power);

			var x = {}, y = {};
			scrollBoxObject.getPosition(x, y);

			var w = {}, h = {};
			scrollBoxObject.getScrolledSize(w, h);
			var maxX = Math.max(0, w.value - scrollBoxObject.width);
			var maxY = Math.max(0, h.value - scrollBoxObject.height);
			scrollBoxObject.scrollTo(newX, newY);
			return false;
		};
		window['piro.sakura.ne.jp'].animationManager.addTask(
			this.smoothScrollTask,
			0, 0, this.smoothScrollDuration
		);
	},
	smoothScrollTask : null,
  
	scrollToTab : function(aTab) 
	{
		if (!aTab || this.isTabInViewport(aTab)) return;

		var b = this.mTabBrowser;

		var scrollBoxObject = this.scrollBoxObject;
		var w = {}, h = {};
		try {
			scrollBoxObject.getScrolledSize(w, h);
		}
		catch(e) { // Tab Mix Plus
			return;
		}

		var targetTabBox = aTab.boxObject;
		var baseTabBox = aTab.parentNode.firstChild.boxObject;

		var xOffset = this.getXOffsetOfTab(aTab);
		var yOffset = this.getYOffsetOfTab(aTab);

		var targetX = (aTab.boxObject.screenX + xOffset < scrollBoxObject.screenX) ?
			(targetTabBox.screenX + xOffset - baseTabBox.screenX) - (targetTabBox.width * 0.5) :
			(targetTabBox.screenX + xOffset - baseTabBox.screenX) - scrollBoxObject.width + (targetTabBox.width * 1.5) ;

		var targetY = (aTab.boxObject.screenY + yOffset < scrollBoxObject.screenY) ?
			(targetTabBox.screenY + yOffset - baseTabBox.screenY) - (targetTabBox.height * 0.5) :
			(targetTabBox.screenY + yOffset - baseTabBox.screenY) - scrollBoxObject.height + (targetTabBox.height * 1.5) ;

		this.scrollTo(targetX, targetY);
	},
 
	scrollToTabSubTree : function(aTab) 
	{
		var b          = this.mTabBrowser;
		var descendant = this.getDescendantTabs(aTab);
		var lastVisible = aTab;
		for (var i = descendant.length-1; i > -1; i--)
		{
			if (descendant[i].getAttribute(this.kCOLLAPSED) == 'true') continue;
			lastVisible = descendant[i];
			break;
		}

		if (this.isTabInViewport(aTab) && this.isTabInViewport(lastVisible)) {
			return;
		}

		var containerPosition = b.mStrip.boxObject[this.positionProp];
		var containerSize     = b.mStrip.boxObject[this.sizeProp];
		var parentPosition    = aTab.boxObject[this.positionProp];
		var lastPosition      = lastVisible.boxObject[this.positionProp];
		var tabSize           = lastVisible.boxObject[this.sizeProp];

		if (lastPosition - parentPosition + tabSize > containerSize - tabSize) { // out of screen
			var endPos = parentPosition - this.getFirstTab(b).boxObject[this.positionProp] - tabSize * 0.5;
			var endX = this.isVertical ? 0 : endPos ;
			var endY = this.isVertical ? endPos : 0 ;
			this.scrollTo(endX, endY);
		}
		else if (!this.isTabInViewport(aTab) && this.isTabInViewport(lastVisible)) {
			this.scrollToTab(aTab);
		}
		else if (this.isTabInViewport(aTab) && !this.isTabInViewport(lastVisible)) {
			this.scrollToTab(lastVisible);
		}
		else if (parentPosition < containerPosition) {
			this.scrollToTab(aTab);
		}
		else {
			this.scrollToTab(lastVisible);
		}
	},
   
/* show/hide tab bar (backward compatibility) */ 
	get tabbarShown() { return this.autoHide.tabbarShown; },
	set tabbarShown(aValue) { return this.autoHide.tabbarShown = aValue; },
	get tabbarExpanded() { return this.autoHide.tabbarExpanded; },
	set tabbarExpanded(aValue) { return this.autoHide.tabbarExpanded = aValue; },
	get togglerSize() { return this.autoHide.togglerSize; },
	set togglerSize(aValue) { return this.autoHide.togglerSize = aValue; },
	get sensitiveArea() { return this.autoHide.sensitiveArea; },
	set sensitiveArea(aValue) { return this.autoHide.sensitiveArea = aValue; },
	get lastMouseDownTarget() { return this.autoHide.lastMouseDownTarget; },
	set lastMouseDownTarget(aValue) { return this.autoHide.lastMouseDownTarget = aValue; },

	get tabbarWidth() { return this.autoHide.tabbarWidth; },
	set tabbarWidth(aValue) { return this.autoHide.tabbarWidth = aValue; },
	get tabbarHeight() { return this.autoHide.tabbarHeight; },
	set tabbarHeight(aValue) { return this.autoHide.tabbarHeight = aValue; },
	get splitterWidth() { return this.autoHide.splitterWidth; },

	set autoHideShown() { return this.autoHide.shown; },
	set autoHideShown(aValue) { return this.autoHide.shown = aValue; },
	set autoHideXOffset() { return this.autoHide.XOffset; },
	set autoHideYOffset() { return this.autoHide.YOffset; },
	get autoHideMode() { return this.autoHide.mode; },
	set autoHideMode(aValue) { return this.autoHide.mode = aValue; },

	updateAutoHideMode : function() { this.autoHide.updateAutoHideMode(); },
	showHideTabbarInternal : function(aReason) { this.autoHide.showHideTabbarInternal(aReason); },
	showTabbar : function(aReason) { this.autoHide.showTabbar(aReason); },
	hideTabbar : function(aReason) { this.autoHide.hideTabbar(aReason); },
	redrawContentArea : function() { this.autoHide.redrawContentArea(); },
	drawTabbarCanvas : function() { this.autoHide.drawTabbarCanvas(); },
	get splitterBorderColor() { this.autoHide.splitterBorderColor; },
	clearTabbarCanvas : function() { this.autoHide.clearTabbarCanvas(); },
	updateTabbarTransparency : function() { this.autoHide.updateTabbarTransparency(); },

	get autoHideEnabled() { return this.autoHide.enabled; },
	set autoHideEnabled(aValue) { return this.autoHide.enabled = aValue; },
	startAutoHide : function() { this.autoHide.start(); },
	endAutoHide : function() { this.autoHide.end(); },
	startAutoHideForFullScreen : function() { this.autoHide.startForFullScreen(); },
	endAutoHideForFullScreen : function() { this.autoHide.endForFullScreen(); },

	startListenMouseMove : function() { this.autoHide.startListenMouseMove(); },
	endListenMouseMove : function() { this.autoHide.endListenMouseMove(); },
	get shouldListenMouseMove() { return this.autoHide.shouldListenMouseMove; },
	showHideTabbarOnMousemove : function() { this.autoHide.showHideTabbarOnMousemove(); },
	cancelShowHideTabbarOnMousemove : function() { this.autoHide.cancelShowHideTabbarOnMousemove(); },
	showTabbarForFeedback : function() { this.autoHide.showTabbarForFeedback(); },
	delayedShowTabbarForFeedback : function() { this.autoHide.delayedShowTabbarForFeedback(); },
	cancelHideTabbarForFeedback : function() { this.autoHide.cancelHideTabbarForFeedback(); }
  
}; 

TreeStyleTabBrowser.prototype.__proto__ = TreeStyleTabService;