title: XAML tooltips are being clipped
body: <p>I am trying to make a WPF app (regular Windows app, not XBAP or Silverlight).
  I want the main app window to support transparency, and show through the desktop below.</p>
  
  <p>But when I specify ToolTip text on a Button, the ToolTip appears <em>beneath</em> (z-order) the main window!</p>
  
  <p>I have a screenshot where:
  * Another app overlapps and blocks view of the partially transparent main window.
  * The tooltip from my button appears in front of the other app.
  * Where the tooltip is not in front of the other app, it is <em>behind</em> the partial transparency.</p>
  
  <p>I read elsewhere that this is a known problem with the WPF engine for 32-bit XP and does not occur in Vista.</p>
  
  <p>What I am looking for is a fix/workaround.</p>