How can I create non-rectangular windows
Check out this Microsoft KB article, Shaped Windows Forms and Controls in Visual Studio .NET
There are 2 ways to create non-rectangular windows:
1) The Control.Region property (Form inherits this of course):
2) Use the Form.TransparencyKey property. This tells the form not to paint any pixels that match the color of the TransparencyKey. So you can make your fancy skin bitmap, then set the TransparencyKey to be, say Color.Red,
then all the pixels that are RGB(255,0,0) will be transparent.
(from sburke_online@microsoft..nospam..com on microsoft.public.dotnet.framework.windowsforms)