After upgrading to Ubuntu 9.10 “Karmic” I had some problems using Eclipse 3.5 “Galileo”. Some buttons did not show any reaction, especially the installation of new plugins or the update of already installed plugins did not work. The solution was to explicitly set the environment variable GDK_NATIVE_WINDOWS to true, preferably by using a shell script to start Eclipse
#!/bin/sh export GDK_NATIVE_WINDOWS=true YOUR_COMMAND_TO_START_ECLIPSE
See also:
→ Bug 291257 – [Widgets] Buttons functionality problem with GTK+ 2.18
→ Migrating to client-side windows
