Nimbus causes icons in each tab heading/title/caption whatever it's called to be squeezed up against the text. It also makes the 'spreadsheet lines' in the entity table and elsewhere disappear completely.
'Motif' gets rid of the fuzziness problem but the colours are not great and all the text is jagged, not anti-aliased.
Doesn't "Tools => Preferences" tab "Miscellaneous" just affect the output window (that's what it says)?
Cheers,
Paul