I have a modal popup that initially shows some content but expands a div if a checkbox is selected. The modal expands correctly but doesn\'t recenter unless you scroll up or
Be careful that this isn't tied to the resize event of the window. If it is, your recentering could trigger a resize event in IE, which would cause an infinte loop.
If it is tied to the resize event, allow 1 or 2 resize events to occur, but then ignore the rest. (I say 2, because in IE, a "restore" event on the window will trigger at least 2 resize events (3 in IE6).
Whatever event you have bound to the scrolling to get it to re-center, bind that event to the checkbox/div expanding event as well (or call it from within the other event). Hard to say more without seeing some code.
Here is what it is:
$find('ModalPopupExtenderClientID')._layout();
For example:
$find('detailsPopUpExtenderId')._layout();
and in aspx:
<ccl:ModalPopupExtender runat="server" ID="MyPopUpExtender" TargetControlID="pop" PopupControlID="PopUp" BehaviorID="detailsPopUpExtenderId" BackgroundCssClass="ModalBackground" />
BehaviorID
being the property where to set the clientside id.