If you tried Eclipse Juno, you may see that the tab fonts are “large”. The “Package Explorer” and “Outlet” tab font take a lot of space.
If you take a look in the preferences, in the appearance section, you won’t find anything related to these tabs.
The good news is that Eclipse use CSS for the main style, and you can edit these CSS.
If you take a look in
ECLIPSE_HOME/plugins/org.eclipse.platform_4.2.0.v201206081400/css, you will find the different CSS used. On Linux, if you use the GTK style (in the Preferences/Appearances), the
e4_default_gtk.css is used.
Edit this file and change the .MPartStack section :
font-family: "Droid Sans";