Static switcher background flicker

[kolya]

Way to reproduce:

1) enable static switcher.

2) Press alt+tab

3) Release tab and hold alt

After some time background starts to flicker. It looks like switcher's window transparency changes momentarily and then goes back. Also shadow becomes more pronounced in the same moment.
It looks like this happens only when system is relatively idle. It doesn't seem to be happening if one application does active screen output, like terminal with 'tail -f' for some actively updated file.

Expected behaviour - no sudden background flickering.

Switcher (not 'static') also has this problem but it is only reproducible if transparency/brightness/saturation are set to 100 and zooming is disabled.

This problem didn't exist in compiz that came with Ubuntu Natty.

[kolya (mar-kolya)]

I've tried to do some 'gdb-ing' but after several hours I got nothing useful. It is possible though that I was just looking in the wrong place.

I would be happy to help diagnosing this issue but I would need a little help on where I should start looking.

Thanks.

[kolya (mar-kolya)]

Some additional information about this bug: it looks like it is being caused by screen updates that happening while static switcher is being shown.

I've tried new-clean account with all clean profile and Iwas able to reproduce bug on two different machines: the only thing user needs to do it to put 'System Monitor' applet on to the panel (I'm using Mate DE). Once applet if there is starts rendering cpu usage and stuff and this cause flicker to be very prominent.

Hope this helps finding the root cause.

Thanks!

[Eleni Maria Stea (hikiko)]

Thank you for taking the time to report that bug. As part of a general clean-up we decided to close it since the static switcher is not part of the unity desktop and has conflicts with the unityshell plugin. Therefore I changed the status to Won't Fix.

[voidstarstar (voidstarstar)]

Does this workaround fix this? In CCSM, under Utility make sure Workarounds is enabled. Then in Workarounds check the box for "Force full screen redraws (buffer swap) on repaint".

If this bug is to be marked as Won't Fix, does that imply that the Application Switcher is considered a depreciated feature and will be removed? There are still many people that use this that don't use Unity.

[Jarrod Farrell (jarrodmaddy)]

@voidstarstar

This workaround works, but the help text "Forces the entire screen to redraw every repaint. [...] will cause a massive increase in CPU and GPU usage" gives me hesitation especially when I'm a laptop where an increase of use is, well, bad for mobility.

Enabling doesn't increase it as drastically as it says and taking a terminal window with htop on a trip across my workspaces with the setting on or off doesn't change how intensive compiz has to work in any discernible way.

Also the Won't Fix status is confusing too. Because what /is/ the alternative to the application switcher?