diff --git a/content/treestyletab/res/prefs.js b/content/treestyletab/res/prefs.js
index 510aedff..b52c8a90 100644
--- a/content/treestyletab/res/prefs.js
+++ b/content/treestyletab/res/prefs.js
@@ -25,7 +25,7 @@
    http://www.cozmixng.org/repos/piro/fx3-compatibility-lib/trunk/prefs.js
 */
 (function() {
-	const currentRevision = 1;
+	const currentRevision = 2;
 
 	if (!('piro.sakura.ne.jp' in window)) window['piro.sakura.ne.jp'] = {};
 
@@ -47,20 +47,30 @@
 			return this._Prefs;
 		},
 		_Prefs : null,
-	 
-		getPref : function(aPrefstring) 
+
+		get DefaultPrefs() 
 		{
+			if (!this._DefaultPrefs) {
+				this._DefaultPrefs = Components.classes['@mozilla.org/preferences-service;1'].getService(Components.interfaces.nsIPrefService).getDefaultBranch(null);
+			}
+			return this._DefaultPrefs;
+		},
+		_DefaultPrefs : null,
+	 
+		getPref : function(aPrefstring, aBranch) 
+		{
+			if (!aBranch) aBranch = this.Prefs;
 			try {
-				switch (this.Prefs.getPrefType(aPrefstring))
+				switch (aBranch.getPrefType(aPrefstring))
 				{
 					case this.Prefs.PREF_STRING:
-						return decodeURIComponent(escape(this.Prefs.getCharPref(aPrefstring)));
+						return decodeURIComponent(escape(aBranch.getCharPref(aPrefstring)));
 						break;
 					case this.Prefs.PREF_INT:
-						return this.Prefs.getIntPref(aPrefstring);
+						return aBranch.getIntPref(aPrefstring);
 						break;
 					default:
-						return this.Prefs.getBoolPref(aPrefstring);
+						return aBranch.getBoolPref(aPrefstring);
 						break;
 				}
 			}
@@ -69,10 +79,16 @@
 
 			return null;
 		},
-	 
-		setPref : function(aPrefstring, aNewValue) 
+
+		getDefaultPref : function(aPrefstring)
 		{
-			var pref = this.Prefs ;
+			return this.getPref(aPrefstring, this.DefaultPrefs);
+		},
+	 
+		setPref : function(aPrefstring, aNewValue, aBranch) 
+		{
+			if (!aBranch) aBranch = this.Prefs;
+
 			var type;
 			try {
 				type = typeof aNewValue;
@@ -84,17 +100,22 @@
 			switch (type)
 			{
 				case 'string':
-					pref.setCharPref(aPrefstring, unescape(encodeURIComponent(aNewValue)));
+					aBranch.setCharPref(aPrefstring, unescape(encodeURIComponent(aNewValue)));
 					break;
 				case 'number':
-					pref.setIntPref(aPrefstring, parseInt(aNewValue));
+					aBranch.setIntPref(aPrefstring, parseInt(aNewValue));
 					break;
 				default:
-					pref.setBoolPref(aPrefstring, aNewValue);
+					aBranch.setBoolPref(aPrefstring, aNewValue);
 					break;
 			}
 			return true;
 		},
+
+		setDefaultPref : function(aPrefstring)
+		{
+			return this.setPref(aPrefstring, aNewValue, this.DefaultPrefs);
+		},
 	 
 		clearPref : function(aPrefstring) 
 		{
diff --git a/content/treestyletab/treestyletab.js b/content/treestyletab/treestyletab.js
index 45c0d8e8..6442e481 100644
--- a/content/treestyletab/treestyletab.js
+++ b/content/treestyletab/treestyletab.js
@@ -466,11 +466,6 @@ var TreeStyleTabService = {
 
 		var pref = isVertical ? 'tabbar.fixed.vertical' : 'tabbar.fixed.horizontal' ;
 		this.setTreePref(pref, !this.getTreePref(pref));
-
-		if (!this.getTreePref('syncRelatedPrefs')) return;
-
-		if (!isVertical)
-			this.setTreePref('enableSubtreeIndent', !this.getTreePref(pref));
 	},
  
 	changeTabbarPosition : function(aNewPosition) /* PUBLIC API */ 
@@ -480,12 +475,6 @@ var TreeStyleTabService = {
 
 		aNewPosition = aNewPosition.toLowerCase();
 		this.setTreePref('tabbar.position', aNewPosition);
-
-		if (!this.getTreePref('syncRelatedPrefs')) return;
-
-		var vertical = (aNewPosition == 'left' || aNewPosition == 'right');
-		this.setTreePref('enableSubtreeIndent', vertical || !this.getTreePref('tabbar.fixed.horizontal'));
-		this.setTreePref('allowSubtreeCollapseExpand', vertical);
 	},
   
 /* backward compatibility */ 
@@ -1170,6 +1159,25 @@ var TreeStyleTabService = {
 		this.overrideExtensionsPreInit(); // hacks.js
 
 		this.registerTabFocusAllowance(this.defaultTabFocusAllowance);
+
+		// migrate old prefs
+		switch (this.getTreePref('orientalPrefsMigrated'))
+		{
+			case 0:
+				[
+					'extensions.treestyletab.tabbar.fixed',
+					'extensions.treestyletab.enableSubtreeIndent',
+					'extensions.treestyletab.allowSubtreeCollapseExpand'
+				].forEach(function(aPref) {
+					let value = this.getPref(aPref);
+					if (value === null) return;
+					this.setPref(aPref+'.horizontal', value);
+					this.setPref(aPref+'.vertical', value);
+				}, this);
+			default:
+				break;
+		}
+		this.setTreePref('orientalPrefsMigrated', 1);
 	},
 	preInitialized : false,
 	
diff --git a/content/treestyletab/treestyletabbrowser.js b/content/treestyletab/treestyletabbrowser.js
index b3c87459..4cebdbdb 100644
--- a/content/treestyletab/treestyletabbrowser.js
+++ b/content/treestyletab/treestyletabbrowser.js
@@ -502,7 +502,6 @@ TreeStyleTabBrowser.prototype = {
 		this.onPrefChange('extensions.treestyletab.tabbar.style');
 		this.onPrefChange('extensions.treestyletab.twisty.style');
 		this.onPrefChange('extensions.treestyletab.showBorderForFirstTab');
-		this.onPrefChange('extensions.treestyletab.enableSubtreeIndent');
 		this.onPrefChange('extensions.treestyletab.tabbar.invertTabContents');
 		this.onPrefChange('extensions.treestyletab.tabbar.invertScrollbar');
 		this.onPrefChange('extensions.treestyletab.tabbar.invertClosebox');
@@ -844,7 +843,7 @@ TreeStyleTabBrowser.prototype = {
 			b.mStrip.removeAttribute('height');
 			b.mPanelContainer.removeAttribute('height');
 
-			this.updateTabbarFixedState();
+			this.updateTabbarState();
 
 			if (pos == this.kTABBAR_RIGHT) {
 				b.setAttribute(this.kTABBAR_POSITION, 'right');
@@ -919,7 +918,7 @@ TreeStyleTabBrowser.prototype = {
 			b.setAttribute(this.kMODE, this.getTreePref('tabbar.multirow') ? 'multirow' : 'horizontal' );
 			b.removeAttribute(this.kTAB_INVERTED);
 
-			this.updateTabbarFixedState();
+			this.updateTabbarState();
 
 			if (pos == this.kTABBAR_BOTTOM) {
 				b.setAttribute(this.kTABBAR_POSITION, 'bottom');
@@ -961,16 +960,19 @@ TreeStyleTabBrowser.prototype = {
 		scrollInnerBox = null;
 		allTabsButton = null;
 	},
-	updateTabbarFixedState : function()
+	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()) {
@@ -983,6 +985,18 @@ TreeStyleTabBrowser.prototype = {
 				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);
+
+		this.updateAllTabsIndent();
 	},
   
 	destroy : function() 
@@ -1127,14 +1141,6 @@ TreeStyleTabBrowser.prototype = {
 				}, this);
 				break;
 
-			case 'extensions.treestyletab.enableSubtreeIndent':
-				if (value)
-					b.setAttribute(this.kINDENTED, 'true');
-				else
-					b.removeAttribute(this.kINDENTED);
-				this.updateAllTabsIndent();
-				break;
-
 			case 'extensions.treestyletab.tabbar.style':
 				if (value) {
 					if (/^(default|vertigo|mixed)$/.test(value))
@@ -1189,13 +1195,6 @@ TreeStyleTabBrowser.prototype = {
 					b.removeAttribute(this.kHIDE_ALLTABS);
 				break;
 
-			case 'extensions.treestyletab.allowSubtreeCollapseExpand':
-				if (value)
-					b.setAttribute(this.kALLOW_COLLAPSE, true);
-				else
-					b.removeAttribute(this.kALLOW_COLLAPSE);
-				break;
-
 			case 'extensions.treestyletab.tabbar.autoHide.mode':
 				this.updateAutoHideMode();
 				break;
@@ -1209,9 +1208,13 @@ TreeStyleTabBrowser.prototype = {
 					this.endListenMouseMove();
 				break;
 
+			case 'extensions.treestyletab.enableSubtreeIndent.horizontal':
+			case 'extensions.treestyletab.enableSubtreeIndent.vertical':
+			case 'extensions.treestyletab.allowSubtreeCollapseExpand.horizontal':
+			case 'extensions.treestyletab.allowSubtreeCollapseExpand.vertical':
 			case 'extensions.treestyletab.tabbar.fixed.vertical':
 			case 'extensions.treestyletab.tabbar.fixed.horizontal':
-				this.updateTabbarFixedState();
+				this.updateTabbarState();
 				break;
 
 			case 'extensions.treestyletab.tabbar.transparent.style':
@@ -2939,7 +2942,8 @@ TreeStyleTabBrowser.prototype = {
 
 		var b = this.mTabBrowser;
 		if (!aProp) {
-			aProp = this.getTreePref('enableSubtreeIndent') ? this.indentProp : null ;
+			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;
diff --git a/defaults/preferences/treestyletab.js b/defaults/preferences/treestyletab.js
index b7baa4ff..4588f8ae 100644
--- a/defaults/preferences/treestyletab.js
+++ b/defaults/preferences/treestyletab.js
@@ -39,9 +39,11 @@ pref("extensions.treestyletab.tabbar.togglerSize", 5);
 pref("extensions.treestyletab.tabbar.fixed.horizontal", true);
 pref("extensions.treestyletab.tabbar.fixed.vertical", false);
 pref("extensions.treestyletab.syncRelatedPrefs", true);
-pref("extensions.treestyletab.enableSubtreeIndent",    true);
+pref("extensions.treestyletab.enableSubtreeIndent.horizontal", false);
+pref("extensions.treestyletab.enableSubtreeIndent.vertical",   true);
 pref("extensions.treestyletab.enableSubtreeIndent.allTabsPopup", true);
-pref("extensions.treestyletab.allowSubtreeCollapseExpand", true);
+pref("extensions.treestyletab.allowSubtreeCollapseExpand.horizontal", false);
+pref("extensions.treestyletab.allowSubtreeCollapseExpand.vertical",   true);
 pref("extensions.treestyletab.showBorderForFirstTab",  false);
 pref("extensions.treestyletab.autoExpand.enabled",     true);
 pref("extensions.treestyletab.autoExpand.delay",       500);
@@ -114,5 +116,8 @@ pref("extensions.multipletab.show.multipletab-selection-item-removeTabSubTree",
 pref("extensions.treestyletab.TMP.doNotUpdate.isTabVisible", false);
 
 
+pref("extensions.treestyletab.orientalPrefsMigrated", 0);
+
+
 pref("extensions.treestyletab@piro.sakura.ne.jp.name", "chrome://treestyletab/locale/treestyletab.properties");
 pref("extensions.treestyletab@piro.sakura.ne.jp.description", "chrome://treestyletab/locale/treestyletab.properties");