See this example
http://blogs.msdn.com/llobo/archive/2006/02/24/538757.aspx
This however does'nt work with XAML files that have class files associated with them.
The other issue is that this does'nt fit into the XAML app structure, Application, Window, Page etc. It would make a lot more sense for this to be factored into the Application or Windows\NavigationWindow classes's.
Non rectangle window in WPF
joe123163029
DHRITIMAN BANERJEE
Andrew,
The fact that creating a non-rectangular window is not possible using the Window class is certainly a hole in the story, and one that we'd like to fix in the future. I do appreciate the feedback. Hopefully the workaround on Lester's blog will work for you for now -- we would certainly appreciate more feedback if your scenarios are still completely blocked even when using the approach that Lester describes.
Regards,
Lauren [MS]