title: How to use System.Windows in Mono / MonoDevelop?
body: <p>I'm trying to use the Rect structure from System.Windows in MonoDevelop, but I can't find System.Windows in the packages list when I try to add a reference to it.  There are lots of things like System.Windows.Controls.... and System.Windows.Forms... but not System.Windows by itself.  How do I get access to Rect in MonoDevelop?</p>