I have a problem with a Winforms application written in Visual Studio 2005 (C#). It has a MDI main form with one maximized mdi child form. In Windows XP the child form is perfectly resized and maximized with the MDI Parent.
With Windows Vista (Enterprise and Business) resizing works great, but when you maximize the MDI form the child form is not perfectly maximized. There is about a 8 pixel gap on the right hand side. The child form still performs as if it is maximized, it just does not look very good. If you manually stretch the form to fill the desktop it looks fine – it is only when the MDI is set to maximize that the gap appears.
It’s a known issue that hasn’t been fixed yet it seems (I’m having it as well on Windows Server 2008).
You can find more information and a possible fix in this thread on MSDN forums:
Problem with maximized MDI child window