Warning message when no default road is found

git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@6475 8aca7d54-2c30-db11-9de9-000461428c89
FIX: set ticker region dirty if ticker empty

git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@6476 8aca7d54-2c30-db11-9de9-000461428c89
FIX: mark icons dirty if tool is no longer selected

git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@6477 8aca7d54-2c30-db11-9de9-000461428c89
FIX: use dirty flag when displaying the zeiger

git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@6478 8aca7d54-2c30-db11-9de9-000461428c89