<

if(this._onResizeDelegate){

$removeHandler(window,"resize",this._onResizeDelegate);

this._onResizeDelegate=null;

}

This part of the code seems fine.
However, _initializeDimensions has:

if(navigator.userAgent.toLowerCase().indexOf("msie")!=-1){

this._onResizeDelegate=Function.createDelegate(this,this.onWindowResize);

setTimeout(function(){

$addHandler(window,"resize",_1._onResizeDelegate);

},0);

}else{

this._onResizeDelegate=Function.createDelegate(this,this.onWindowResize);

$addHandler(window,"resize",this._onResizeDelegate);

}

The problem is that the resize delegate is saved before the handler is actually added via a call to setTimeout. If the window's location changes before this setTimeout method runs, an exception is thrown because $removeHandler is called when $addHandler never was.
I believe the corrected code would be as follows:

if(navigator.userAgent.toLowerCase().indexOf("msie")!=-1){

setTimeout(function(){

this._onResizeDelegate=Function.createDelegate(this,this.onWindowResize);

$addHandler(window,"resize",_1._onResizeDelegate);

},0);

}else{

this._onResizeDelegate=Function.createDelegate(this,this.onWindowResize);

$addHandler(window,"resize",this._onResizeDelegate);

}

Simply move setting the resize delegate inside anonymous delegate executed by setTimeout. This way, if setTimeout never runs, the resize delegate is null and $removeHandler is never called.

If necessary, I can post an example of this error. It's easily reproduced via something like a client-side refresh/redirect.

Thanks for looking into this.

David