It's simple. It happens when i deminimize firefox or thunderbird window (previously minimized). I use "ati" open source driver, but it happens with "radeon" open source driver too.
P.S.: About black screen when I log in, wallpaper gets black not all screen. -- Enabling Desktop Effects, some part of firefox and thunderbird windows are black for few seconds when I deminimize them. https://bugs.launchpad.net/bugs/113086 You received this bug notification because you are a member of Ubuntu Bugs, which is the bug contact for Ubuntu. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs