Eclipse on Linux (GTK+) has rather large UI elements which wastes screen real estate. Compare the Linux version (taken on Ubuntu 9.10):
with the Windows version:
Note the vertical size of the Project Explorer tab, the menubar, and the toolbar. Is it possible to tweak this somehow? How does this look in other Linux distributions?
There are some blog entries for making Eclipse GTK gui less "clumsy". Note that you have to modify the gtkrc file in most cases: