Window artifacts displayed/left behind
Issue raised from https://bugs.launchpad.net/ubuntu/+source/mutter/+bug/1811900
Various window artifacts/alt-tab window remanents are visible when (by default) animations are used on Budgie Desktop.
The above picture show this when the top left button is clicked two times or more.
Budgie uses mutter as its window-manager. This issue first occurred when Mutter moved to v3.30 and is still present in v3.32.
Ubuntu 18.04 uses mutter v3.28 and this issue is not observed. However, Ubuntu have a proposed package built from the git debian salsa 3.28.x branch which exhibits this behaviour.
I have git bisect this branch (https://salsa.debian.org/gnome-team/mutter/commits/upstream/3.28.x)
dad@dad-VirtualBox:~/Downloads/mutter/mutter$ git bisect good
527f6ef8357f614793035a999ec4409ef02470e2 is the first bad commit
commit 527f6ef8357f614793035a999ec4409ef02470e2
Author: Carlos Garnacho <carlosg@gnome.org>
Date: Sat Apr 29 11:43:33 2017 +0000
ClutterActor: Preserve valid paint volumes till the next relayout/repaint
Cuts down approximately all paint volume calculations when there's
windows that redraw frequently, but don't move.
https://bugzilla.gnome.org/show_bug.cgi?id=782344
(cherry picked from commit 161d2540e659fa8ed5efc74f350a741b2430417d)
:040000 040000 058f850980bad70fdd5792a46dbfc33c70fe88c6 bf54863f282d901b9aeb323d00f2a5dfe2d13588 M clutter
Indeed when I reworked a revert patch for this commit, the issue was resolved (see attached) revert_volume_calc.patch
The mutter commit is this on gitlab 161d2540
This issue has been highlighted on all budgie based distro's and distro's that have packaged budgie that also have moved to mutter v3.30/3.32 i.e. Arch/Manjaro & Fedora have reported this issue:
https://github.com/solus-project/budgie-desktop/issues/1627 an https://github.com/solus-project/budgie-desktop/issues/1622
I don't pretend to actually understand what commit is doing or how to interpret a possible fix for budgie animations - but hopefully the above commit is least something to focus on.