Created attachment 74770 [details] graphical glitches while Alt+tabbing Hardware: ATI Mobility X700 Driver: Gallium 0.4 on ATI RV410 Steps to reproduce: (KWIN Effects + Fade is enabled by default) 1. Have at least two simple applications in your taskbar. 2. Press Alt+Tab two times. (Select the exact same application again.) 3. The application often doesn't refresh and the Window Switcher is painted over it. Note: This bug tends to happen less, the more applications you have open. Workaround #1: 1. Disable Fade Effect. (Note: I currently cannot disable Fade Effect because I'm using the Fade Effect as a work around for Debian bug #690428 / KDE Bug# 295254
Created attachment 74771 [details] The window textures from the window switcher often don't disappear after Alt+Tabbing
It smells like bug #306186 BUT: the claimed version is 4.8.4 Also if blurring was enabled, it looks like bug #308557 a) is that version correct? (or are you using 4.9.0?) b) can you reproduce it when disabling "OpenGL 2 shaders" in "kcmshell4 kwincompositing", 3rd tab - resp. using XRender?
(In reply to comment #2) > It smells like bug #306186 BUT: the claimed version is 4.8.4 Yes, I'm running 4.8.4 > Also if blurring was enabled, it looks like bug #308557 Blurring is not enabled. Enabling blurring doesn't help. > a) is that version correct? (or are you using 4.9.0?) 4.8.4 > b) can you reproduce it when disabling "OpenGL 2 shaders" in "kcmshell4 > kwincompositing", 3rd tab - resp. using XRender? Yes, it happens when I disable OpenGL 2 shaders and it also happens when I use only XRender instead of OpenGL. After you alt+tab, the frame around the Window switcher fades away, but the textures that show the window previews often remain painted on the screen. It's like it's missing that final refresh. It happens about 50% of the time. I think it might have something to do with timing. I tried on a different PC using an nVidia graphics chip with proprietary drivers and got the exact same results.
It seems like the slower you are at Alt+tabbing through windows, the more likely you'll end up with the window switcher, or at least parts of it, stuck on your screen when you're finished. It goes away when you start moving windows around and the compositor repaints the windows.
Does it remain only until you trigger a repaint of the area (moving a window around) or permanently? (In reply to comment #3) > Blurring is not enabled. Enabling blurring doesn't help. i just drew some connections here, ie. "it would look the same if..." -> may be a dupe =)
(In reply to comment #5) > Does it remain only until you trigger a repaint of the area (moving a window > around) or permanently? > It is not permanent. It goes away when I trigger a repaint of the area.
I threw a video up on youtube: http://www.youtube.com/watch?v=SJKTYFyo0ig
the important question is whether that issue is still valid with 4.9 as the Fade Effect has been rewritten.
I'm pretty sure this one is fixed with 4.9. I remember that I used to see this issue, but since quite some time I have not seen it. For testing I just enabled very slow animation and it nicely fades the thumbnails. If you are able to reproduce with 4.9 or 4.10 please reopen.