gmoccapy_1_3_3 - initialize mouse button mode corrected

ver. 1.3.3
- the combobox for the mouse button mode has not been initialized
  correct, if it had the default value of the glade file. It is a
  bug in glade. The work around is not to set a default value in glade
  but in the python code.


Signed-off-by: Norbert Schechner <nieson@web.de>