effects/slidingpopups: Schedule workspace repaints
For optimization purposes, kwin will ignore repaint regions scheduled by invisible windows, e.g. hidden docks, minimized windows, etc.
The problem is that it sort of breaks w->addRepaintFull(). If a lot of animation frames are dropped, for example due to heavy cpu load, the sliding popups animation can jump from the middle of animation right up to the end. It will schedule a repaint but it will be ignored.
In order to work around that issue, this change makes the sliding popups effect schedule workspace repaints in postPaintScreen() to ensure that the Scene will always repaint dirty regions.
Hopefully, this should fix bugs where auto-hide panels sometimes flicker on Wayland.
Edited by Vlad Zahorodnii