Using DwmExtendFrameIntoClientArea causes window to oddly resize

I have an application that uses DwmExtendFrameIntoClientArea to draw a glass effect area at the top of my .NET Form. A str开发者_开发知识库ange side effect is that when you maximize and restore the window it grows taller. So if you keep maximizing/restoring it just keeps getting taller! Remove the call to DwmExtendFrameIntoClientArea to remove that nice effect and it stops going wrong.

Any ideas?