GNOME Bugzilla – Bug 740359
Background windows sometimes flicker through foreground full-screen apps (like anaconda), when a tooltip disappears
Last modified: 2015-02-02 15:02:45 UTC
Created attachment 290981 [details] bug demonstration video I was just testing F21 TC2 installation inside a VM, when I noticed that when I display a tooltip and then make it disappears, the background window flickers through anaconda briefly. Please see attached video. I used this image: http://dl.fedoraproject.org/pub/alt/stage/21_TC2/Workstation/x86_64/iso/Fedora-Live-Workstation-x86_64-21-TC2.iso but updated anaconda to this bodhi update before running it: https://admin.fedoraproject.org/updates/python-blivet-0.61.10-1.fc21,anaconda-21.48.15-1.fc21 Packages: gnome-shell-3.14.1.5-1.fc21.x86_64 mutter-3.14.1.5-1.fc21.x86_64 clutter-1.20.0-1.fc21.x86_64 anaconda-21.48.15-1.fc21.x86_64 My VM uses spice+qxl. The flickering was very much reproducible during that single installation, it happened in 50% of cases when a tooltip disappeared. However, when I wanted to reproduce it afterwards, it was much harder. My findings: 1. It's possible to reproduce that with original anaconda from TC2, as well as updated anaconda. So anaconda version is not relevant. 2. I could only reproduce it if there was some other window behind anaconda. It could exist before running anaconda, or started afterwards, that didn't matter. After I triggered the issue, the window could be closed and it flickered to background. But some window had to be there in the first place if I were to trigger it. 3. I could only reproduce that after I've set the root password and returned to the installation progress screen. 4. Sometimes I had to make the tooltip appear and disappear a large number of times (20-30x) before it started happening. Maybe it's somehow related to the installation itself? Progress bar reaching some value? Anaconda doing something in the background? No idea.
It really seems somehow connected to time or progress of installation. If I wait long enough (installation progress reaches ~40%), I can trigger the problem easily and almost instantly. I even didn't have to fill in the root password (enter the dialog). The issue happened immediately and cancelling the tooltip for the first or second time. Reliably.
Looks like the main anaconda window is getting unredirected and then redirected briefly when the tooltip is up. These transitions cause that kind of flickering unfortunately. It that's indeed the case, the easy fix is for anaconda to set an hint on its windows to not be unredirected. The WM spec defines _NET_WM_BYPASS_COMPOSITOR, see http://standards.freedesktop.org/wm-spec/wm-spec-latest.html .
(In reply to comment #2) > Looks like the main anaconda window is getting unredirected and then redirected > briefly when the tooltip is up. These transitions cause that kind of flickering > unfortunately. It doesn't have to flicker and actually it shouldn't if we get the ordering right. At least that's what Owen told me when I implemented it and afaik the ordering is correct.
kparal, before starting the installer can you: 1) hit alt-f2 2) type lg 3) type Meta.disable_unredirect_for_screen(global.screen) 4) hit escape and then start the installer and see if it still happens?
(In reply to comment #4) > 1) hit alt-f2 > 2) type lg > 3) type Meta.disable_unredirect_for_screen(global.screen) > 4) hit escape Hi Ray, if I do that, there's no flickering.
Created attachment 295094 [details] rawhide video I can reproduce the same problem in current Rawhide, this image: http://koji.fedoraproject.org/koji/taskinfo?taskID=8504388 Sometimes it happens more often, sometimes less, after a certain part of the installation has passed, it doesn't take too much effort to trigger it.
Created attachment 295095 [details] rpm -qa from rawhide mutter-3.15.3-1.fc22.x86_64 clutter-1.21.2-1.fc22.x86_64 clutter-gst2-2.0.12-4.fc22.x86_64 clutter-gtk-1.6.0-1.fc22.x86_64 gnome-shell-3.15.3-1.fc22.x86_64 anaconda-22.13-1.fc22.x86_64
*** This bug has been marked as a duplicate of bug 743858 ***