title: ICSharpCode.SharpDevelop.Gui.WpfWorkbench - Can't find the containing assembly
body: <p>I write a plugin in C#, where the hosting application handles me an instance of <code>WpfWorkbench</code> in order to allow me to add contols to it's UI (it's actually sort of a hack... anyway I get the <code>WpfWorkbench</code> instance in runtime).</p>
  
  <p>Problem is, I can't cast the returned object from <code>Window</code> to <code>WpfWorkbench</code> in my code, since I don't have the <code>ICSharpCode.SharpDevelop.Gui</code> namespace reference in my project.</p>
  
  <p>I have downloaded <a href="http://www.icsharpcode.net/OpenSource/SD/Download/#SharpDevelop4x" rel="nofollow"><code>SharpDevelop 4.4</code> framework</a> and tried to find the class reference in it's Dll's, but was unsuccessful. </p>
  
  <p>I'm not an experienced VS user, so I think I might just missed an obvious thing. Should I expect to find the <code>GUI</code> namespace in the framework? Or is it some sort of an Add-in?</p>