FIX: Tooltips force the check for backbround redraw.

git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@6456 8aca7d54-2c30-db11-9de9-000461428c89
spaces again... sorry

git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@6457 8aca7d54-2c30-db11-9de9-000461428c89