This applies to Ubuntu 12.04 with KDE and the QtCurve GTK+ theme.
E4 CSS Editor which is not included in Juno by default, but can be installed via the Update Manager.
With this editor, you can change the
font-familyproperties of the
MPartStackstyle used by the editor tabs.
Update 14 Aug 2012: If you develop web applications and edit CSS files in Eclipse, you'd better deinstall the E4 CSS editor after customizing the workbench layout to fall back to the standard WTP CSS editor. The XText-based E4 editor does not recognize some legal syntax like unquoted URLs.
Actually, you don't need any Eclipse plugin to change the CSS, you can directly edit the CSS file in your Eclipse installation at