code: def on_size(self, event):
          '''handle window size changes'''
          state = self.state
          self.need_redraw = True
          if state.report_size_changes:
              # tell owner the new size
              size = self.frame.GetSize()
              if size != self.last_size:
                  self.last_size = size
                  state.out_queue.put(MPImageNewSize(size)f on_size(self, event):
          '''handle window size changes'''
          state = self.state
          self.need_redraw = True
          if state.report_size_changes:
              # tell owner the new size
              size = self.frame.GetSize()
              if size != self.last_size:
                  self.last_size = size
                  state.out_queue.put(MPImageNewSize(size))
docs: handle window size changes