diff --git a/modules/base.js b/modules/base.js
index 3a995419..46cc235a 100644
--- a/modules/base.js
+++ b/modules/base.js
@@ -37,24 +37,23 @@ const EXPORTED_SYMBOLS = ['TreeStyleTabBase'];
 
 const Cc = Components.classes;
 const Ci = Components.interfaces;
- 
+
 Components.utils.import('resource://gre/modules/XPCOMUtils.jsm');
-XPCOMUtils.defineLazyModuleGetter(this, 'Services', 'resource://gre/modules/Services.jsm');
+Components.utils.import('resource://gre/modules/Services.jsm');
 
-Components.utils.import('resource://treestyletab-modules/lib/prefs.js');
-Components.utils.import('resource://treestyletab-modules/lib/namespace.jsm');
-var window = getNamespaceFor('piro.sakura.ne.jp');
-
-XPCOMUtils.defineLazyModuleGetter(this, 'Deferred', 'resource://treestyletab-modules/lib/jsdeferred.js');
+XPCOMUtils.defineLazyGetter(this, 'window', function() {
+	Cu.import('resource://treestyletab-modules/lib/namespace.jsm');
+	return getNamespaceFor('piro.sakura.ne.jp');
+});
+XPCOMUtils.defineLazyGetter(this, 'prefs', function() {
+	Cu.import('resource://treestyletab-modules/lib/prefs.js');
+	return window['piro.sakura.ne.jp'].prefs;
+});
 XPCOMUtils.defineLazyGetter(this, 'jstimer', function() {
 	var jstimer = {};
 	Components.utils.import('resource://treestyletab-modules/lib/jstimer.jsm', jstimer);
 	return jstimer;
 });
-XPCOMUtils.defineLazyGetter(this, 'boxObject', function() {
-	Components.utils.import('resource://treestyletab-modules/lib/boxObject.js', {});
-	return window['piro.sakura.ne.jp'].boxObject;
-});
 XPCOMUtils.defineLazyGetter(this, 'extensions', function() {
 	Components.utils.import('resource://treestyletab-modules/lib/extensions.js', {});
 	return window['piro.sakura.ne.jp'].extensions;
@@ -69,9 +68,16 @@ XPCOMUtils.defineLazyGetter(this, 'autoScroll', function() {
 });
 XPCOMUtils.defineLazyModuleGetter(this, 'UninstallationListener',
   'resource://treestyletab-modules/lib/UninstallationListener.js');
+XPCOMUtils.defineLazyModuleGetter(this, 'Deferred',
+  'resource://treestyletab-modules/lib/jsdeferred.js');
 XPCOMUtils.defineLazyModuleGetter(this, 'confirmWithPopup', 'resource://treestyletab-modules/lib/confirmWithPopup.js');
 XPCOMUtils.defineLazyModuleGetter(this, 'utils', 'resource://treestyletab-modules/utils.js', 'TreeStyleTabUtils');
 
+if (Services.appinfo.OS === 'WINNT') {
+	XPCOMUtils.defineLazyModuleGetter(this, 'AeroPeek',
+	  'resource://gre/modules/WindowsPreviewPerTab.jsm', 'AeroPeek');
+}
+
 
 var TreeStyleTabBase = { 
 	__proto__ : window['piro.sakura.ne.jp'].prefs,
@@ -290,7 +296,8 @@ var TreeStyleTabBase = {
 	get animationManager() { return animationManager; },
 	get autoScroll() { return autoScroll; },
 	get Deferred() { return Deferred; },
- 
+	get AeroPeek() { return AeroPeek; }, // for Windows
+
 	init : function utils_init() 
 	{
 		if (this._initialized) return;
@@ -321,14 +328,6 @@ var TreeStyleTabBase = {
 		this.onPrefChange('extensions.treestyletab.counter.role.horizontal');
 		this.onPrefChange('extensions.treestyletab.counter.role.vertical');
 
-		try {
-			if (Services.appinfo.OS == 'WINNT')
-				this.updateAeroPeek();
-		}
-		catch(e) {
-			dump(e+'\n');
-		}
-
 		try {
 			this.overrideExtensions();
 		}
@@ -511,13 +510,6 @@ var TreeStyleTabBase = {
 		});
 	},
 
-	updateAeroPeek : function utils_updateAeroPeek() 
-	{
-		var ns = {};
-		Components.utils.import('resource://gre/modules/WindowsPreviewPerTab.jsm', ns);
-		this.AeroPeek = ns.AeroPeek;
-	},
- 
 	overrideExtensions : function utils_overrideExtensions() 
 	{
 		// Scriptish
@@ -611,23 +603,7 @@ var TreeStyleTabBase = {
 	},
  
 /* utilities */ 
-	
-	getBoxObjectFor : function utils_getBoxObjectFor(aNode) 
-	{
-		return boxObject.getBoxObjectFor(aNode);
-	},
- 
-	evalInSandbox : function utils_evalInSandbox(aCode, aOwner) 
-	{
-		try {
-			var sandbox = new Components.utils.Sandbox(aOwner || 'about:blank');
-			return Components.utils.evalInSandbox(aCode, sandbox);
-		}
-		catch(e) {
-		}
-		return void(0);
-	},
- 
+
 	get browserWindow() 
 	{
 		return this.topBrowserWindow;
diff --git a/modules/browser.js b/modules/browser.js
index e9661a69..b2e73933 100644
--- a/modules/browser.js
+++ b/modules/browser.js
@@ -3959,7 +3959,7 @@ TreeStyleTabBrowser.prototype = {
 			return;
 
 		var indexes = [];
-		var items = this.evalInSandbox('('+this.SessionStore.getClosedTabData(this.window)+')');
+		var items = utils.evalInSandbox('('+this.SessionStore.getClosedTabData(this.window)+')');
 		for (let i = 0, maxi = items.length; i < maxi; i++)
 		{
 			let item = items[i];
diff --git a/modules/lib/boxObject.js b/modules/lib/boxObject.js
deleted file mode 100644
index d6e7d144..00000000
--- a/modules/lib/boxObject.js
+++ /dev/null
@@ -1,180 +0,0 @@
-/*
- "getBoxObjectFor()" compatibility library for Firefox 3.6 or later
-
- Usage:
-   // use instead of HTMLDocument.getBoxObjectFor(HTMLElement)
-   var boxObject = window['piro.sakura.ne.jp']
-                         .boxObject
-                         .getBoxObjectFor(HTMLElement);
-
- license: The MIT License, Copyright (c) 2009-2010 YUKI "Piro" Hiroshi
-   http://www.cozmixng.org/repos/piro/fx3-compatibility-lib/trunk/license.txt
- original:
-   http://www.cozmixng.org/repos/piro/fx3-compatibility-lib/trunk/boxObject.js
-   http://www.cozmixng.org/repos/piro/fx3-compatibility-lib/trunk/boxObject.test.js
-   http://www.cozmixng.org/repos/piro/fx3-compatibility-lib/trunk/fixtures/box.html
-*/
-
-/* To work as a JS Code Module */
-if (typeof window == 'undefined' ||
-	(window && typeof window.constructor == 'function')) {
-	this.EXPORTED_SYMBOLS = ['boxObject'];
-
-	// If namespace.jsm is available, export symbols to the shared namespace.
-	// See: http://www.cozmixng.org/repos/piro/fx3-compatibility-lib/trunk/namespace.jsm
-	try {
-		let ns = {};
-		Components.utils.import('resource://treestyletab-modules/lib/namespace.jsm', ns);
-		/* var */ window = ns.getNamespaceFor('piro.sakura.ne.jp');
-	}
-	catch(e) {
-		window = {};
-	}
-}
-
-(function() {
-	const currentRevision = 6;
-
-	if (!('piro.sakura.ne.jp' in window)) window['piro.sakura.ne.jp'] = {};
-
-	var loadedRevision = 'boxObject' in window['piro.sakura.ne.jp'] ?
-			window['piro.sakura.ne.jp'].boxObject.revision :
-			0 ;
-	if (loadedRevision && loadedRevision > currentRevision) {
-		return;
-	}
-
-	var Cc = Components.classes;
-	var Ci = Components.interfaces;
-
-	window['piro.sakura.ne.jp'].boxObject = {
-		revision : currentRevision,
-
-		getBoxObjectFor : function(aNode, aUnify)
-		{
-			return ('getBoxObjectFor' in aNode.ownerDocument) ?
-					this.getBoxObjectFromBoxObjectFor(aNode, aUnify) :
-					this.getBoxObjectFromClientRectFor(aNode, aUnify) ;
-		},
-
-		getBoxObjectFromBoxObjectFor : function(aNode, aUnify)
-		{
-			var boxObject = aNode.ownerDocument.getBoxObjectFor(aNode);
-			var box = {
-					x       : boxObject.x,
-					y       : boxObject.y,
-					width   : boxObject.width,
-					height  : boxObject.height,
-					screenX : boxObject.screenX,
-					screenY : boxObject.screenY,
-					element : aNode
-				};
-			if (!aUnify) return box;
-
-			var style = this._getComputedStyle(aNode);
-			box.left = box.x - this._getPropertyPixelValue(style, 'border-left-width');
-			box.top = box.y - this._getPropertyPixelValue(style, 'border-top-width');
-			if (style.getPropertyValue('position') == 'fixed') {
-				box.left -= frame.scrollX;
-				box.top  -= frame.scrollY;
-			}
-			box.right  = box.left + box.width;
-			box.bottom = box.top + box.height;
-
-			return box;
-		},
-
-		getBoxObjectFromClientRectFor : function(aNode, aUnify)
-		{
-			var box = {
-					x       : 0,
-					y       : 0,
-					width   : 0,
-					height  : 0,
-					screenX : 0,
-					screenY : 0,
-					element : aNode
-				};
-			try {
-				var zoom = this.getZoom(aNode.ownerDocument.defaultView);
-
-				var rect = aNode.getBoundingClientRect();
-				if (aUnify) {
-					box.left   = rect.left;
-					box.top    = rect.top;
-					box.right  = rect.right;
-					box.bottom = rect.bottom;
-				}
-
-				var style = this._getComputedStyle(aNode);
-				var frame = aNode.ownerDocument.defaultView;
-
-				// "x" and "y" are offset positions of the "padding-box" from the document top-left edge.
-				box.x = rect.left + this._getPropertyPixelValue(style, 'border-left-width');
-				box.y = rect.top + this._getPropertyPixelValue(style, 'border-top-width');
-				if (style.getPropertyValue('position') != 'fixed') {
-					box.x += frame.scrollX;
-					box.y += frame.scrollY;
-				}
-
-				// "width" and "height" are sizes of the "border-box".
-				box.width  = rect.right - rect.left;
-				box.height = rect.bottom - rect.top;
-
-				box.screenX = rect.left * zoom;
-				box.screenY = rect.top * zoom;
-
-				box.screenX += frame.mozInnerScreenX * zoom;
-				box.screenY += frame.mozInnerScreenY * zoom;
-			}
-			catch(e) {
-			}
-
-			'x,y,screenX,screenY,width,height,left,top,right,bottom'
-				.split(',')
-				.forEach(function(aProperty) {
-					if (aProperty in box)
-						box[aProperty] = Math.round(box[aProperty]);
-				});
-
-			return box;
-		},
-
-		_getComputedStyle : function(aNode)
-		{
-			return aNode.ownerDocument.defaultView.getComputedStyle(aNode, null);
-		},
-
-		_getPropertyPixelValue : function(aStyle, aProperty)
-		{
-			return parseInt(aStyle.getPropertyValue(aProperty).replace('px', ''));
-		},
-
-		Prefs : Cc['@mozilla.org/preferences;1']
-			.getService(Ci.nsIPrefBranch)
-			.QueryInterface(Ci.nsIPrefBranch2),
-
-		getZoom : function(aFrame)
-		{
-			try {
-				if (!this.Prefs.getBoolPref('browser.zoom.full'))
-					return 1;
-			}
-			catch(e) {
-				return 1;
-			}
-			var markupDocumentViewer = aFrame.top
-					.QueryInterface(Ci.nsIInterfaceRequestor)
-					.getInterface(Ci.nsIWebNavigation)
-					.QueryInterface(Ci.nsIDocShell)
-					.contentViewer
-					.QueryInterface(Ci.nsIMarkupDocumentViewer);
-			return markupDocumentViewer.fullZoom;
-		}
-
-	};
-})();
-
-if (window != this) { // work as a JS Code Module
-	this.boxObject = window['piro.sakura.ne.jp'].boxObject;
-}
diff --git a/modules/utils.js b/modules/utils.js
index 446b9ce4..7546eb70 100644
--- a/modules/utils.js
+++ b/modules/utils.js
@@ -39,21 +39,22 @@ let EXPORTED_SYMBOLS = ['TreeStyleTabUtils'];
 
 const Cc = Components.classes;
 const Ci = Components.interfaces;
+const Cu = Components.utils;
 
-Components.utils.import('resource://gre/modules/XPCOMUtils.jsm');
+Cu.import('resource://gre/modules/XPCOMUtils.jsm');
 
 XPCOMUtils.defineLazyGetter(this, 'window', function() {
-	Components.utils.import('resource://treestyletab-modules/lib/namespace.jsm');
+	Cu.import('resource://treestyletab-modules/lib/namespace.jsm');
 	return getNamespaceFor('piro.sakura.ne.jp');
 });
 
 XPCOMUtils.defineLazyGetter(this, 'prefs', function() {
-	Components.utils.import('resource://treestyletab-modules/lib/prefs.js');
+	Cu.import('resource://treestyletab-modules/lib/prefs.js');
 	return window['piro.sakura.ne.jp'].prefs;
 });
 
 XPCOMUtils.defineLazyGetter(this, 'stringBundle', function() {
-	Components.utils.import('resource://treestyletab-modules/lib/stringBundle.js', {});
+	Cu.import('resource://treestyletab-modules/lib/stringBundle.js', {});
 	return window['piro.sakura.ne.jp'].stringBundle;
 });
 
@@ -89,6 +90,17 @@ let TreeStyleTabUtils = {
 	},
 	get tabbrowserBundle () {
 		return stringBundle.get('chrome://browser/locale/tabbrowser.properties');
+	},
+
+	evalInSandbox : function utils_evalInSandbox(aCode, aOwner)
+	{
+		try {
+			var sandbox = new Cu.Sandbox(aOwner || 'about:blank');
+			return Cu.evalInSandbox(aCode, sandbox);
+		}
+		catch(e) {
+		}
+		return void(0);
 	}
 
 };