I can confirm this bug on maverick and found a way to reproduce it. It only occurs with fglrx and not with ati as graphics driver. (Radeon Mobility 5650) It only occurs on gnome and not on kde.
After fglrx 2:8.780-0ubuntu2 I tried 8.780 from ati.com with the similar results. How to reproduce: Install and start the qt-designer $ sudo apt-get install qt4-designer $ designer-qt4 Open a QWidget window: File -> new -> Widget -> new Add a QTabWidget Select the QWidget and chose a layout (i.e. QVBoxLayout) Click and hold the lower right corner of the QWidget Form and increase the window size. Gnome/X crashes and shows the gdm-greeter. It seems every Qt/KDE-application containing a big, resizeable tab-widget can cause a Gnome crash on my notebook. For now Gnome is unusable for me and I have to use KDE... -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/539440 Title: gtkwidget.c:5636: widget not within a GtkWindow -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs