I decided to move to Ubuntu for my Android development and for this, I installed Eclipse 3.5.1 but noticed Eclipse is behaving strangely. The buttons didn’t work properly and install new software was completely useless.
After spending hours searching Net I found that this is an issue with the new GTKWindows which. To solve this, you need to use
"export GDK_NATIVE_WINDOWS=true" in a terminal and then start Eclipse in the same terminal.
This off course is an interim solution till Eclipse team figure out what has been broken.