Telerik RadWindow And AdjustResizing Problem In FireFox (Scroll Bars Appear)

I am so confused for setting the width and height of DIV and FIELDSET inside A RadWindow. When I browse my radwindow in firefox with this code:

setTimeout(function() { GetRadWindow().autoSize(true) }, 500); 

every thing is ok in IE 8 - but in Firefox I have scrolls bars.

How can I remove them?

My width and height of div and fieldset are like :

<style type="text/css"> 
html, body, form 
{ 
    padding: 0; 
    margin: 0; 
    height: 100%; 
    background-color: #f2f2de; 
} 
fieldset 
{ 
    height: 581px; 
} 
* + html fieldset 
{ 
    height: 585px; 
    width: 840px; 
} 

<div style="width: 8开发者_C百科50px; height: 600px;"> 

How can I fix this problem ?

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Make sure that you are using XHTML - compliant Doctype in your content page - this should help.

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i asked about this issue from telerik team and they told me in new versions this problem is solved.plz look at my Question Date And This Answer Date...
i think this problem has been solved in newer versions / however this problem has nothing to do with Doctype...