When using Eclipse 3.5 on Ubuntu 9.10 you will discover display problems in some dialog boxes. The problem is the combination of Compiz and Eclipse. To implement a workaround for this problem simply create a start script in the eclipse folder (/opt/eclipse in my case) with the following content:
#! /bin/sh
#
# Fix display problem on Ubuntu 9.10
#
export GDK_NATIVE_WINDOWS=true
/opt/eclipse/eclipse