diff --git a/content/treestyletab/config.js b/content/treestyletab/config.js
index 68547002..c8a52ff4 100644
--- a/content/treestyletab/config.js
+++ b/content/treestyletab/config.js
@@ -55,12 +55,17 @@ function onChangeGroupBookmarkRadio()
 
 function onChangeTabbarPosition(aOnChange)
 {
+	const XULAppInfo = Components.classes['@mozilla.org/xre/app-info;1']
+			.getService(Components.interfaces.nsIXULAppInfo);
+	const comparator = Components.classes['@mozilla.org/xpcom/version-comparator;1']
+						.getService(Components.interfaces.nsIVersionComparator);
+
 	var pos = document.getElementById('extensions.treestyletab.tabbar.position-radiogroup').value;
 	var invertScrollbar = document.getElementById('extensions.treestyletab.tabbar.invertScrollbar-check');
 	invertScrollbar.disabled = pos != 'left';
 	document.getElementById('extensions.treestyletab.tabbar.invertUI-check').disabled = pos != 'right';
 
-	if (isGecko18()) {
+	if (comparator.compare(XULAppInfo.version, '3.0') < 0) {
 		invertScrollbar.removeAttribute('collapsed');
 	}
 	else {
@@ -74,7 +79,6 @@ function onChangeTabbarPosition(aOnChange)
 	var collapseCheck = document.getElementById('extensions.treestyletab.allowSubtreeCollapseExpand-check');
 //	var autoHideCheck = document.getElementById('extensions.treestyletab.tabbar.autoHide.enabled-check');
 	var hideNewTabCheck = document.getElementById('extensions.treestyletab.tabbar.hideNewTabButton-check');
-	var hideAllTabsCheck = document.getElementById('extensions.treestyletab.tabbar.hideAlltabsButton-check');
 
 	if (aOnChange &&
 		gLastStateIsVertical != (pos == 'left' || pos == 'right')) {
@@ -85,26 +89,20 @@ function onChangeTabbarPosition(aOnChange)
 	if (pos == 'left' || pos == 'right') {
 		indentCheck.setAttribute('collapsed', true);
 //		autoHideCheck.removeAttribute('collapsed');
-		hideNewTabCheck.removeAttribute('collapsed');
-		hideAllTabsCheck.removeAttribute('collapsed');
+		if (comparator.compare(XULAppInfo.version, '3.1b3') >= 0)
+			hideNewTabCheck.removeAttribute('collapsed');
+		else
+			hideNewTabCheck.setAttribute('collapsed', true);
 	}
 	else {
 		indentCheck.removeAttribute('collapsed');
 //		autoHideCheck.setAttribute('collapsed', true);
 		hideNewTabCheck.setAttribute('collapsed', true);
-		hideAllTabsCheck.setAttribute('collapsed', true);
 	}
 
 	gTabbarPlacePositionInitialized = true;
 }
 
-function isGecko18()
-{
-	const XULAppInfo = Components.classes['@mozilla.org/xre/app-info;1'].getService(Components.interfaces.nsIXULAppInfo);
-	var version = XULAppInfo.platformVersion.split('.');
-	return parseInt(version[0]) <= 1 && parseInt(version[1]) <= 8;
-}
-
 
 var gAutoHideModeRadio;
 var gAutoHideModeToggle;
diff --git a/content/treestyletab/config.xul b/content/treestyletab/config.xul
index a61d756a..f9c31696 100644
--- a/content/treestyletab/config.xul
+++ b/content/treestyletab/config.xul
@@ -103,15 +103,15 @@
 				label="&config.allowSubtreeCollapseExpand;"/>
 		</hbox>
 		<hbox align="center">
+			<checkbox id="extensions.treestyletab.tabbar.hideAlltabsButton-check"
+				preference="extensions.treestyletab.tabbar.hideAlltabsButton"
+				label="&config.tabbar.hideAlltabsButton;"/>
 			<checkbox id="extensions.treestyletab.enableSubtreeIndent-check"
 				preference="extensions.treestyletab.enableSubtreeIndent"
 				label="&config.enableSubtreeIndent;"/>
 			<checkbox id="extensions.treestyletab.tabbar.hideNewTabButton-check"
 				preference="extensions.treestyletab.tabbar.hideNewTabButton"
 				label="&config.tabbar.hideNewTabButton;"/>
-			<checkbox id="extensions.treestyletab.tabbar.hideAlltabsButton-check"
-				preference="extensions.treestyletab.tabbar.hideAlltabsButton"
-				label="&config.tabbar.hideAlltabsButton;"/>
 		</hbox>
 		</vbox>
 	</groupbox>
diff --git a/content/treestyletab/treestyletab.css b/content/treestyletab/treestyletab.css
index 92c945a1..43044bff 100644
--- a/content/treestyletab/treestyletab.css
+++ b/content/treestyletab/treestyletab.css
@@ -27,18 +27,18 @@ tabbrowser[treestyletab-tabbar-fixed="true"] .tabbrowser-strip+splitter {
 }
 
 
-tabbrowser:not([treestyletab-mode="horizontal"]) .tabbrowser-arrowscrollbox > .scrollbutton-up,
-tabbrowser:not([treestyletab-mode="horizontal"]) .tabbrowser-arrowscrollbox > .scrollbutton-down-stack,
-tabbrowser:not([treestyletab-mode="horizontal"]) .tabbrowser-arrowscrollbox > .scrollbutton-down, /* Firefox 3 */
+tabbrowser[treestyletab-mode="vertical"] .tabbrowser-arrowscrollbox > .scrollbutton-up,
+tabbrowser[treestyletab-mode="vertical"] .tabbrowser-arrowscrollbox > .scrollbutton-down-stack,
+tabbrowser[treestyletab-mode="vertical"] .tabbrowser-arrowscrollbox > .scrollbutton-down, /* Firefox 3 */
 tabbrowser[treestyletab-hide-alltabs-button="true"] .tabs-alltabs-stack,
 tabbrowser[treestyletab-hide-alltabs-button="true"] .tabbrowser-arrowscrollbox ~ stack, /* "all tabs" button in Firefox 3 and 3.1 */
 tabbrowser[treestyletab-mode="vertical"] .tabs-closebutton-box,
-tabbrowser:not([treestyletab-mode="horizontal"]) .tab-drop-indicator-bar,
-tabbrowser:not([treestyletab-mode="horizontal"]) #vide-bar, /* Tab Mix Plus */
-tabbrowser:not([treestyletab-mode="horizontal"]) #tabs-scroll-up-down-box, /* Tab Mix Plus */
-tabbrowser:not([treestyletab-mode="horizontal"]) #alltabs-place-holder, /* Tab Mix Plus */
-tabbrowser:not([treestyletab-mode="horizontal"]) .tabs-scroll /* Tab Mix Plus */ {
-	display: none !important;
+tabbrowser[treestyletab-mode="vertical"] .tab-drop-indicator-bar,
+tabbrowser[treestyletab-mode="vertical"] #vide-bar, /* Tab Mix Plus */
+tabbrowser[treestyletab-mode="vertical"] #tabs-scroll-up-down-box, /* Tab Mix Plus */
+tabbrowser[treestyletab-mode="vertical"] #alltabs-place-holder, /* Tab Mix Plus */
+tabbrowser[treestyletab-mode="vertical"] .tabs-scroll /* Tab Mix Plus */ {
+	visibility: collapse !important;
 }
 
 #appcontent {
diff --git a/content/treestyletab/treestyletab.js b/content/treestyletab/treestyletab.js
index 5c95ac7d..5ad18915 100644
--- a/content/treestyletab/treestyletab.js
+++ b/content/treestyletab/treestyletab.js
@@ -166,21 +166,35 @@ var TreeStyleTabService = {
 	_WindowMediator : null,
 
 	get isGecko18() {
-		var version = this.XULAppInfo.platformVersion.split('.');
-		return parseInt(version[0]) <= 1 && parseInt(version[1]) <= 8;
+		if (this._isGecko18 === null)
+			this._isGecko18 = this.Comparator.compare(this.XULAppInfo.version, '3.0') < 0;
+		return this._isGecko18;
 	},
+	_isGecko18 : null,
 	get isGecko19() {
-		var version = this.XULAppInfo.platformVersion.split('.');
-		return parseInt(version[0]) >= 2 || parseInt(version[1]) >= 9;
+		if (this._isGecko19 === null)
+			this._isGecko19 = this.Comparator.compare(this.XULAppInfo.version, '3.0') >= 0;
+		return this._isGecko19;
 	},
-
+	_isGecko19 : null,
 	get XULAppInfo() {
 		if (!this._XULAppInfo) {
-			this._XULAppInfo = Components.classes['@mozilla.org/xre/app-info;1'].getService(Components.interfaces.nsIXULAppInfo);
+			this._XULAppInfo = Components
+					.classes['@mozilla.org/xre/app-info;1']
+					.getService(Components.interfaces.nsIXULAppInfo);
 		}
 		return this._XULAppInfo;
 	},
 	_XULAppInfo : null,
+	get Comparator() {
+		if (!this._Comparator) {
+			this._Comparator = Components
+					.classes['@mozilla.org/xpcom/version-comparator;1']
+					.getService(Components.interfaces.nsIVersionComparator);
+		}
+		return this._Comparator;
+	},
+	_Comparator : null,
 
 	get stringbundle() {
 		if (!this._stringbundle) {
diff --git a/content/treestyletab/treestyletabbrowser.js b/content/treestyletab/treestyletabbrowser.js
index 2357300d..09436689 100644
--- a/content/treestyletab/treestyletabbrowser.js
+++ b/content/treestyletab/treestyletabbrowser.js
@@ -1056,8 +1056,7 @@ TreeStyleTabBrowser.prototype = {
 						break;
 
 					case 'extensions.treestyletab.tabbar.hideAlltabsButton':
-						var pos = b.getAttribute(this.kTABBAR_POSITION);
-						if (value && (pos == 'left' || pos == 'right'))
+						if (value)
 							b.setAttribute(this.kHIDE_ALLTABS, true);
 						else
 							b.removeAttribute(this.kHIDE_ALLTABS);