I have created a feedback item on MS Connect for the issue where Abstract and Generic Controls and Forms arn't supported within the Visual Studio desginers. I was supprised that searching on Connect didn't turn up any previous feedback on the issue.
As a work around I have put up links to here and Urban Potato:
http://www.urbanpotato.net/Default.aspx/userinterface/11/document/2001
http://forums.lhotka.net/forums/thread/336.aspx
Microsoft have closed the issue as a "Resolved (Won't Fix)" but hopefully if enough developers show interest they might include support in Visual Studio out of the box. Here is the link to the issue:
https://connect.microsoft.com/VisualStudio/feedback/ViewFeedback.aspx?FeedbackID=253384
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