It is now possible to switch between Watchfaces (Time/Date).
You see I use the display to debug my code. I dont use the serial monitor. A lot of strange things are happening when i use it. Maybe a conflict with the softserial library for the bluetooth modul.
A second way to debug is the Windows Phone. Visual Express for Windows Phone 8 got a serial monitor too. You can watch the serial traffic and use it as a serial monitor like the serial monitor in Arduino IDE.
A third way will be my new Logic Analyzer (Zeroplus LAB-C 16032). Haven´t connected it to my breadboard yet. But I think the next few days I will do the first tests with this device.