Windows not drawing above OpenGL windows
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I have an app with an OpenGL window as a child window of the main window.

When I display a dialog box above the OpenGL window, it doesn't get drawn. It's like it's not getting WM_PAINT messages.  If I can guess the title bar position of the dialog box, I can drag it and it's still responsive.

I realise this might be a vague question, but I was wondering if anyone else has seen this sort of behaviour before and knew of a solution?

I wondered if the Pixel Format Descriptor would make a difference - I had `PFD_DRAW_TO_WINDOW`, but changing to `PDF_DRAW_TO_BITMAP` didn't make any difference. I'm not sure what else I should be looking at?

Thanks for _any_ help!
