after installing luna I had no theme set which resulted in following UI:
Needless to say, I really like that look. :) When playing with some settings i changed the UI theme and now I can't get back. The combo box where u can set your theme doesn't allow empty selection.
Now I am stuck with the old theme. Help!
Exporting my current workspace settings revealed entries containing following String:
org.eclipse.e4.ui.css.theme.e4_default6.1
Apparently it is the native name of the "Windows 7 classic" Theme in eclipse. Searching my workspaces .metadata folder revealed 12 occurences (I recommend EditPlus or Notepad++ for this). After deleting those I got my clean "null" theme look.
Now I am happy again. :)