Why is Eclipse Luna dark theme ugly?

Fix text editor colors:

Help > Eclipse Marketplace > Search for "Eclipse Color Theme" and install it.

Then go to: Windows > Preferences > General > Appearance > Color Theme

Open a terminal and run

export SWT_GTK3=0

Then start Eclipse :

eclipse

The user interface should be fixed. If this worked for you edit the eclipse launch script for more convenience:

sudo gedit /usr/bin/eclipse

Add

export SWT_GTK3=0

Before:

ECLIPSE=/usr/lib/eclipse/eclipse

Source: https://github.com/guari/eclipse-ui-theme/issues/73