Summary: - After some time running, certain areas of the screen begin to flicker from/to black. No pixels are lost, just areas going black, and being repainted. - Flickering seems to appear in three scenarios: - Most often: when switching to different windows, opening new ones (e.g. the K menu in KDE), opening a new application's window, or closing another. - Occasionally: At random times - Rarely: on scroll, or manual scroll (pressing arrow up/down to scroll the active window). Tried once and noticed a really interesting pattern: - press the arrow-down button => flickering area turns black - press the arrow-down button => flickering area is repainted - press the arrow-down button => just scrolling as normal Subsequent presses of up/down arrow keys to cause a scroll-up/scroll-down keep rotating the above three steps, in exact sequence. Scrolling with the mouse wheel was more difficult, as it scrolls 3 lines or so, therefore the behaviour was not so obvious. In either case, the flickering manifests itself in different, random, single or multiple rectangular areas of the screen. - The issue can be mitigated by moving a window around or making it full-screen, thus causing repaints. Given a rectangular flickering area, if a window is dragged into it causing repaints, only the rectangle MINUS the repainted area flickers. If the whole rectangle is repainted, the flickering stops. Most of the time it restarts when a new window is created. Rolling up a window causes a new flickering scenario most of the time. Often causes only the rolled-up part of the window, the titlebar, to become the only visible part of the screen, whilst everything else is black. Repaints caused by moving windows around can be used to reveal other windows on the desktop. Switching desktop causes a full repaint, making the flickering disappear. In some occasions, it looks like there are multiple flickering areas on top of each other, causing other multi-step patterns, like: - All screen fully painted, as normal - One rectangle turning black, or partially black, or an area of the desktop MINUS parts of it covered by the active window. - Another, different rectangular area of the screen turning black, MINUS areas recently painted by the active window Each of the above steps sometimes repeat sequentially at a few hundred milliseconds distance Switching terminal CTRL-ALT-F1 and back to CTRL-ALT-F7 doesn't help Tried passing various kernel parameters as described on similar, although less detailed bug reports, but nothing seems to have changed. GPU here is Intel, but I've seen nVidia powered laptops with Ubuntu and also Macbooks manifesting a very similar behaviour. It's also very interesting that I recently emerged world/updated everything and for about 2-3 days I had no flickering, then it started again. Also, it looks as if I shut down the laptop, leave it turned off for some time and I cold-start it again, it will run flicker-free again for some hours. I normally run a large number of applications on the computer, use lots of virtual desktops At this point I'm really puzzled to understand where the issue comes from and to get it sorted, as it's been around for years, but I also understand it may be a quite complex one to solve. Driver issue? Most bug reports and requests for help seem to point in this direction, but why would it happen on nVidia, as well, then? And the Mac? X issue? Macbooks used to run Xorg, correct? Maybe a correlation? This very much seems to have something to do with window management. Never experienced this issue in terminal mode. Please help. Feel free to ask questions, more info, config files, let's get creative, let's get it sorted. Happy to recompile things from the kernel up with extra log lines or whatever to help tracing the issue down.
1) This is not a support forum. Try our mailing lists, IRC channels and web forums instead to find the solution to your problem. 2) This report describes a very particular bug (which is good) in a very complex system (bad) with many variables (bad) but fails to point out a specific cause (ugly). Once you have found what cause is, and you suspect the Gentoo Linux distribution can solve it for a larger number of users, do not hesitate to let us know through this bug tracker.
