R – What could cause redraw issues on 64-bit vista but not in 32-bit in .NET WInForms

64-bitredrawwindows-vistawinforms

This happens when compiling for Any Cpu as well as compiling to x86. Sections of the GUI doesn't redraw unless it's resized, for instance if the main form is maximized some of the controls don't resize with it, and others have sections that don't redraw and displays the what was previously there.

This works fine on 32-bit machines, both XP and Vista, but on 64-bit Vista (don't have x64 XP to test with) the redrawing just isn't working properly.

Anyone have any ideas on where to start tracking this down?

Edit: This occurs on 2 separate machines, and at least the one I'm currently on has the latest drivers from NVidia.

Edit2: Running a 32-bit XP virtual machine on my 64-bit machine and the application doesn't exhibit the redrawing issue in the VM

Edit3: It may be a driver issue, but we don't know if or when drivers will fix the issue. A co-worker says there's fewer issues with an ATI card at home than with NVidia, but I've been updating my video drivers pretty much monthly for the past few months and it's still not resolved, so we can't just release our product and just tell our customers that some day the driver manufacturers may get around to fixing this.

Does anyone have any insight on what things to try to avoid? We're compiling as x86 and all our components are x86. I can't seem to reproduce this issue with any of the components in test projects, and I haven't heard anyone else report these issues on most of the the component forums, so it is fairly likely that it's something we're doing.

Best Answer

That sounds horribly like this problem.

When resizing windows on Windows you typically get a chain where each window receives a WM_SIZE message and then calls MoveWindow() (or similar) on its children which in turn receive a WM_SIZE and so on. I'm sure that .NET does the same thing under the covers.

On x64, Windows limits the depth of this nesting, and after a certain point (12-15 nested windows) it will just not send the WM_SIZE messages anymore. This limitation does not appear to exist on x86. This limitation affects both x86 and x64 code running on x64 versions of Windows.

This foxed us for ages, as different x64 installs would show different symptoms. The MSDN blog posting above has some possible workarounds - we ended up using a secondary thread to do the window sizes asynchronously, this solved the problem fairly neatly.

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