I try to use below line to get ID, it works fine in Ext.Net V1.x but create problem with V2.X with IE10.
var f=Ext.get('<%=BtnID.ClientID%>');
as the same get function does't work with any extjs control.
Same thing happen with:
var jj = Ext.get(<%=grd.ClientID %>.getView().getHeaderCell(0).childNodes[0]);