Why are Window Captions Black and Buttons frameless sometimes during debugging

Question

When debugging my Win32 Applications windows and dialogs sometimes (rarely) do not appear in the chosen Windows scheme, but rather reduced or broken:

The Window captions are all black (instead of blue or silver) and without any shadow. The Buttons doe not have any Button shape ("Abbrechen" in the screen shot). The black bar at the lower half is a windows progress bar. It doesn't show any progress when this happens.

The screen shot (details in the center greyed out) was taken from a 64-Bit application debugged under Visual Studio 2010 on XP SP3 x64 and a 10 GB machine. The was plenty of RAM (some GB) spare.

Does anyone have a clue for the reason? I never do non-client area drawing or something.

EDIT: The symptom only occurs when the Visual Studio Debugger has been attached to the program. But even when the application has been detached from the debugger the problem remains. It does not occur when starting the program without debugging.

Answer 1

There are at least two possibilities.

1. You use some other "theme engine" than the XP native, for example Clearlooks, etc. These engines may not always comply with all thing debuggers want, they may leave their message pump unpumped on some implicitly assumed (in debugger) point, and then the drawing just stalls. Same thing often happens when using some virtual desktop manager on windows, windows window manager is simply too hardwired..

2. Even 32bit programs in 32bit windows may run out of handles, this often results in windows starting being rendered with "Fixedsys" font. Your application shows symptoms only for Theme handled portions, which kind of indicates the possibility nr.1 again.

Try inspecting relevant windows with WinSpy and Process Explorer, unreasonable amounts of allocated resources may hint on what kind starvation is going on.