def paintEvent(self, e):
my_node_painter = QtGui.QPainter()
my_rover_painter = QtGui.Painter()
my_node_painter.begin(self)
my_rover_painter.begin(self)
self.draw_rovers(my_rover_painter)
self.draw_nodes(my_node_painter)
my_node_painter.end()
my_rover_painter.end()
