After upgrading to Ubuntu 9.10 (Karmic Koala) some buttons no longer work in Eclipse 3.5. Clicking has no effect but keyboard shortcuts still work.
It looks like Eclipse is doing some
nasty stuff advanced hacking in SWT on GTK. This bug is fixed in 3.6M2 but you can work around the issue in Eclipse 3.5 by launching Eclipse through the following small shell script (assuming Eclipse is installed in /opt/eclipse-3.5):
#!/bin/sh export GDK_NATIVE_WINDOWS=1 /opt/eclipse-3.5/eclipse