diff --git a/modules/browser.js b/modules/browser.js
index c1a63cdd..f36cb64c 100644
--- a/modules/browser.js
+++ b/modules/browser.js
@@ -291,6 +291,11 @@ TreeStyleTabBrowser.prototype = {
 	{
 		return this.isVertical ? this.counterRoleVertical : this.counterRoleHorizontal ;
 	},
+ 
+	get isDestroying()
+	{
+		return !this.mTabBrowser || !this.mTabBrowser.mTabContainer;
+	},
   
 /* utils */ 
 	
@@ -4939,6 +4944,7 @@ TreeStyleTabBrowser.prototype = {
 		var CSSTransitionEnabled = ('Transition' in aTab.style || 'MozTransition' in aTab.style);
 		if (CSSTransitionEnabled) {
 			aTab.__treestyletab__updateTabIndentTask = function(aTime, aBeginning, aChange, aDuration) {
+				if (self.isDestroying) return true;
 				aTab.style.setProperty(self.indentCSSProp, aIndent+'px', 'important');
 				return true;
 			};
@@ -4953,6 +4959,7 @@ TreeStyleTabBrowser.prototype = {
 		var delta       = aIndent - startIndent;
 		var radian      = 90 * Math.PI / 180;
 		aTab.__treestyletab__updateTabIndentTask = function(aTime, aBeginning, aChange, aDuration) {
+			if (self.isDestroying) return true;
 			var indent, finished;
 			if (aTime >= aDuration) {
 				delete aTab.__treestyletab__updateTabIndentTask;
@@ -5521,6 +5528,7 @@ TreeStyleTabBrowser.prototype = {
 		var self   = this;
 		var firstFrame = true;
 		aTab.__treestyletab__updateTabCollapsedTask = function(aTime, aBeginning, aChange, aDuration) {
+			if (self.isDestroying) return true;
 			if (firstFrame) {
 				// The callback must be started before offsetAttr is changed!
 				if (aCallbackToRunOnStartAnimation)
@@ -5724,6 +5732,7 @@ TreeStyleTabBrowser.prototype = {
 		var radian = 90 * Math.PI / 180;
 		var self = this;
 		this.smoothScrollTask = function(aTime, aBeginning, aChange, aDuration) {
+			if (self.isDestroying) return true;
 			var scrollBoxObject = self.scrollBoxObject;
 			if (aTime >= aDuration || this.cancelingPerformingAutoScroll) {
 				if (!this.cancelingPerformingAutoScroll) {
diff --git a/modules/lib/animationManager.js b/modules/lib/animationManager.js
index 6facbdf5..e060ed8c 100644
--- a/modules/lib/animationManager.js
+++ b/modules/lib/animationManager.js
@@ -19,7 +19,7 @@
    // restart after doing something
    window['piro.sakura.ne.jp'].animationManager.start();
 
- license: The MIT License, Copyright (c) 2009-2011 SHIMODA "Piro" Hiroshi
+ license: The MIT License, Copyright (c) 2009-2012 SHIMODA "Piro" Hiroshi
    http://github.com/piroor/fxaddonlibs/blob/master/license.txt
  original:
    http://github.com/piroor/fxaddonlibs/blob/master/animationManager.js
@@ -46,7 +46,7 @@ if (typeof window == 'undefined' ||
 }
 
 (function() {
-	const currentRevision = 9;
+	const currentRevision = 10;
 
 	if (!('piro.sakura.ne.jp' in window)) window['piro.sakura.ne.jp'] = {};
 
@@ -245,6 +245,7 @@ if (typeof window == 'undefined' ||
 					return !finished && (time < aTask.duration);
 				}
 				catch(e) {
+					dump(e+'\n'+e.stack+'\n');
 				}
 				return false;
 			});