How to specify javascript to run when ModalPopupExtender is shown

hmmm... I'm pretty sure that there's a shown event for the MPE... this is off the top of my head, but I think you can add an event handler to the shown event on page_load

function pageLoad(){    var popup = $find('ModalPopupClientID');    popup.add_shown(SetFocus);}function SetFocus(){    $get('TriggerClientId').focus();}

i'm not sure tho if this will help you with calling it from the server side tho

Here's a simple way to do it in markup:

<ajaxToolkit:ModalPopupExtender     ID="ModalPopupExtender2" runat="server"     TargetControlID="lnk_OpenGame"     PopupControlID="Panel1"     BehaviorID="SilverPracticeBehaviorID"  >    <Animations>        <OnShown>             <ScriptAction Script="InitializeGame();" />          </OnShown>    </Animations>                </ajaxToolkit:ModalPopupExtender>

You should use the BehaviorID value mpeBID of your ModalPopupExtender.

function pageLoad() {    $find('mpeBID').add_shown(HideMediaPlayer);}function HideMediaPlayer() {    var divMovie = $get('<%=divMovie.ClientID%>');    divMovie.style.display = "none";}