There's a more straight-forward way to bring back the old tab behavior of the eclipse Juno editor:

  • Go toINSTALL/plugins/org.eclipse.platform_4.2.0.qualifier/css
  • Choose the CSS for the theme that you use
  • Replaceswt-mru-visible: false;withswt-mru-visible: true;
  • Restart eclipse (I haven't tested if that's necessary, at all)

If that doesn't work, also look inINSTALL/configuration/org.eclipse.e4.ui.css.swt.theme/for CSS files.

If you have a look at the css files of the different themes, you can see why switching the theme solves the problem as well.

=>http://wiki.eclipse.org/Eclipse4/CSS

Here is a quick update for anweibel's answer for Eclipse Luna:

The CSS you wanna edit is now located at

  • INSTALL/plugins/org.eclipse.ui.themes_1.0.0.qualifier/css