It looks like the background color for the Editor (set up in Preferences->Fonts) is also used in the Text tab of the Large Data Editor. However, the background color is only applied behind characters (not in the empty parts of the editor) and the text color is not applied (it's always black).
I would suggest leaving the Large Data Editor black-on-white, regardless of the Editor color preferences.
version 8.0.0.1476
