title: ClientScript.RegisterStartupScript not working
body: <p>I have searched SO &amp; google, but I can't seem to get this to work.
  The code is in the codebehind click event of a  "Cancel" button in my asp.net application but does not seem to close the popup window. Any ideas?</p>
  
  <pre><code>try
  {
      if (btnCancel.Text == "Close")
      {
          String csName1 = "PopupScript";
          Type csType = this.GetType();
  
          ClientScriptManager cs = Page.ClientScript;
          if (!cs.IsClientScriptBlockRegistered(csType, csName1))
          {
              ClientScript.RegisterStartupScript(GetType(), "ClosePopup", "window.close();", true);
          }
      }
  }  
  </code></pre>
  
  <p><strong>Update:</strong> After postback, when I look at the source page, the only code I see related is:  </p>
  
  <pre><code>//&lt;![CDATA[
  (function() {var fn = function() {$get("ToolkitScriptManager1_HiddenField").value = '';Sys.Application.remove_init(fn);};Sys.Application.add_init(fn);})();window.close();
  document.getElementById('ValidationSummary1').dispose = function() {
      Array.remove(Page_ValidationSummaries, document.getElementById('ValidationSummary1'));
  }
  </code></pre>