title: ModalPopupExtender won't render in front of everything in IE7/IE8 Compatibility mode
body: <p>I have a ModalPopupExtender from the AjaxControlToolkit that is working properly in Firefox, Chrome and IE8, but when I run it in IE8 Compatibility mode, it pops up behind the content of my page, rather than on top.<br>
  The popup is in a user control that's rendered by the Masterpage.  What I think is happening is it's popping up in front of the master page content, as the Masterpage content (my header and sidebars) is greyed out, but the content placeholders are rendering in front of my popup.  I found a solution online that suggested changing your doctype declaration in the master page to:</p>
  
  <pre><code>&lt;!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN""http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"&gt;
  </code></pre>
  
  <p>But I already had that exact declaration and still have the positioning problem.  Here is the popup code:</p>
  
  <pre><code>&lt;cc1:ModalPopupExtender ID="ModalPopupExtender1" runat="server"
      TargetControlID="lnkbtnDealerID"
      PopupControlID="pnlPopup"
      BackgroundCssClass="modalBackground"
      DropShadow="true"
      OkControlID="OkButton"
      CancelControlID="CancelButton"
      OnOkScript=""
      &gt;
  &lt;/cc1:ModalPopupExtender&gt;
  
    &lt;asp:Panel ID="pnlPopup" runat="server" CssClass="modalPopup" Style="display: none"     Width="233px"&gt;
     &lt;p&gt;Are you sure?  Your current shopping cart is valid only for the current Dealer ID.      Switching Dealer IDs will reset your cart according to the new Dealer ID chosen.&lt;/p&gt;
  
     &lt;br /&gt;
     &lt;div align="center"&gt;
        &lt;asp:Button ID="OkButton" runat="server" Text="Ok" /&gt;
        &lt;asp:Button ID="CancelButton" runat="server" Text="Cancel" /&gt;
     &lt;/div&gt;
     &lt;/asp:Panel&gt;
  </code></pre>
  
  <p>And the relevant CSS:</p>
  
  <pre><code>.popupControl {
      background-color: white;
      position:absolute;
  visibility:hidden;
  border-style:solid;
  border-color: Black;
  border-width: 2px;
  }
  
  .modalBackground {
  background-color:Gray;
  filter:alpha(opacity=70);
  opacity:0.7;
  }
  
  .modalPopup {
  background-color:white;
  border-width:1px;
  border-style:solid;
  border-color:Gray;
  padding:3px;
  width:250px;
  }
  </code></pre>