'Called when the window is resized to a new `width` and `height`.'

def on_resize(self, width, height):

    self.label.y = (height - 10)
    if self.reticle:
        self.reticle.delete()
    (x, y) = ((self.width // 2), (self.height // 2))
    n = 10
    self.reticle = pyglet.graphics.vertex_list(4, ('v2i', ((x - n), y, (x + n), y, x, (y - n), x, (y + n))))
