I recently made a mistake. I upgraded Kubuntu to the latest version. At first glance everything looked fine, however I quickly realized that something went wrong when I tried to use Eclipse. Opening some dialogs made Eclipse segfault. Reinstalling Eclipse did not work so I took the route to the Eclipse bugtracker and found bug #440660. As it seems the Oxygen GTK theme which is used by KDE to make GTK application "look nice" is incompatible with the Eclipse SWT library. Swichting to another GTK theme was not an option. Luckily the bug report shows a work-a-round to fix the problem:
Edit "/usr/share/themes/oxygen-gtk/gtk-2.0/gtkrc" and change
GtkComboBox::appears-as-list = 1
GtkComboBox::appears-as-list = 0
Eclipse does not segfault anymore!