Thanks for Your advice(s)!

But it is solved. I think it had nothing to do with BIAB but with some parameters of my grafic card or the newly installed Windows 10.

Congratulations for the new BIAB & Realband 2016. The chord sheet is really much easier to use and the other features I have still to explore.

All the best
Koloman from Austria

(Koloman was an irish or scottish prince who was on the way to the holy land killed by our ancestors here in my little town Stockerau in the year 1012. They thought he is a spy. But 2 years later he was canonized and is now Saint Koloman. Times are changing)