Blank screen proglem, after the grid load/update data, when put a FileUploadField in the popup window.

[Aidan]

I put a fileuploadfield in a window,
show blank scren after grid load data.

<ext:GridPanel>
<TopBar>
<ext:Toolbar>
  <Items>
    <ext:Button>
     <Listeners>
      <Click Handler='#{winFileUpload}.Show();' />
     </Listeners>
    </ext:Button>
  </Items>
</ext:Toolbar>
</TopBar>
<Store>
 <ext:Store OnReadData="GetMsg">
  <Proxy>
   <ext:PageProxy/>
  </Proxy>
 </ext:Store>
</Store>
<ColumnModel>
 <Columns>
   <ext:RowNumbererColumn />
 </Columns>
<ColumnModel>
</ext:GridPanel>
<ext:Window Title='Upload File' id='winFileUpload'>
 <items>
  <ext:Form>
   <items>
    <ext:FileUploadField />
   </items>
  </ext:Form>
 </items>
</ext:Window>