title: Modal Popup Extender auto closing after .Show()
body: <p>I am using ModalPopupExtender from AjaxToolkit for asp.net. I am trying to have a ModalPopupExtender triggered with different buttons. The problem is that unless I am using the TargetControlID the popup opens and quickly closes within under a second. I need this popup to be accessible 
  by several different buttons with the same panel being used everytime.</p>
  
  <p>The code below should replicate the problem nicely, on my actual application it almost works fine. Even content being updated with the chosen panel of the popup except that it closes after about 1/2 sec when i call .show() from OnClientClick;</p>
  
  <pre><code>&lt;html xmlns="http://www.w3.org/1999/xhtml"&gt;
  &lt;head id="Head1" runat="server"&gt;
  &lt;title&gt;Untitled Page&lt;/title&gt;
  &lt;script language="javascript" type="text/javascript"&gt;
      //Function to Hide ModalPopUp
      function Hidepopup() {
          $find('AjaxPopupHi').hide();
      }
      //Function to Show ModalPopUp
      function Showpopup() {
          $find('AjaxPopupHi').show();
      }
  
  &lt;/script&gt;
  
  &lt;/head&gt;
  
  &lt;form id="form1" runat="server"&gt;
  
  &lt;asp:LinkButton ID="lnk" OnClientClick = "Showpopup()" runat="server" Text="hi"&gt;&lt;/asp:LinkButton&gt;
  
  
  &lt;asp:ScriptManager ID="ScriptManager1" runat="server"&gt;
  &lt;/asp:ScriptManager&gt;
  &lt;br /&gt;
  
  &lt;asp:Button ID="Button_dummy" Style="display: none" runat="server" Text="Button" /&gt;
  
  &lt;ajaxToolKit:ModalPopupExtender ID="mpe" runat="server" BehaviorID="AjaxPopupHi" TargetControlID="Button_dummy" PopupControlID="pnl"
      CancelControlID="close" /&gt;
  
  &lt;!--BELOW panel does not remain OPEN :/--&gt;
  &lt;asp:Panel ID="pnl" runat="server" CssClass="popupPanel"&gt;
      &lt;div&gt;
          Hi!!!
      &lt;/div&gt;
      &lt;asp:Button ID="close" runat="server" Text="Close" /&gt;
  &lt;/asp:Panel&gt;
  
  
   &lt;/form&gt;
  </code></pre>
  
  <p>Thanks</p>