code: def gui_repaint(self, drawDC=None):
          
          DEBUG_MSG("gui_repaint()", 1, self)
          if self.IsShownOnScreen():
              if drawDC is None:
                  drawDC=wx.ClientDC(self)
  
              #drawDC.BeginDrawing()
              drawDC.DrawBitmap(self.bitmap, 0, 0)
              #drawDC.EndDrawing()
              #wx.GetApp().Yield()
          else:
              pass
docs: Performs update of the displayed image on the GUI canvas, using the
          supplied device context.  If drawDC is None, a ClientDC will be used to
          redraw the image.