If you specify a window object as the scene of a text, then you need to specify viz.ORTHO as the parent, not viz.SCREEN. Also, when adding object to the viz.ORTHO layer, the position units are in pixels, not normalized coordinates. Here is sample code:
Code:
self.anweisung = viz.addText("hello",viz.ORTHO,self.CenterWindow,fontSize=32)
self.anweisung.translate(50,50) #50 pixel from bottom left corner of window