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Bug 2101

Summary: CWBackPixel causes weird window flickering on window resize
Product: SDL Reporter: aBothe <a_bothe>
Component: videoAssignee: Sam Lantinga <slouken>
Status: RESOLVED FIXED QA Contact: Sam Lantinga <slouken>
Severity: normal    
Priority: P2    
Version: HG 2.1   
Hardware: x86_64   
OS: Linux   

Description aBothe 2013-09-16 22:40:41 UTC 
See (at least) this code line (I'm not zielmicha!)
https://github.com/zielmicha/SDL2/blob/master/src/video/x11/SDL_x11window.c#L461

I tried to experiment a bit with SDL2 and OpenGL today and noticed that something caused some weird flickering when resizing my nicely drawn SDL2/OpenGL window:
Just after resizing, the background went black and I had to let my OpenGL code redraw the contents.. 
However, after some hours spent with googling I found out that in OpenGL examples where this CWBackPixel flag was not used when creating X windows, there was no flickering while resizing the window.

See http://www.sbin.org/doc/Xlib/chapt_04.html @ "The Window Background" for more info.

If you don't want to make any changes concerning this issue (I'm btw not the only one having trouble with this :-)), how could I reset this really annoying flag after the window creation using SDL API?

Thanks in advance!
Comment 1 Sam Lantinga 2013-09-28 06:49:29 UTC 
According to the documentation either the background pixel or the background pixmap must be set.  I think the default is to have the background pixmap set to None, but I went ahead and set that explicitly.
http://hg.libsdl.org/SDL/rev/48acb5c00c4b

Can you try this change in the latest snapshot?
http://www.libsdl.org/tmp/SDL-2.0.zip

Thanks!
Comment 2 aBothe 2013-09-28 10:47:55 UTC 
Awesome, it's fixed! Thank you! :-)
Comment 3 Sam Lantinga 2013-09-28 17:27:11 UTC 
You're welcome! :)