title: Pyglet on_mouse_click not detected
body: <p>I'm new to Pyglet, but I've messed with Pygame and JFrames before. I'm having trouble with the on_mouse_click() event for Pyglet. It doesn't seem to ever be called, though all the other events (including on_mouse_release and on_mouse_drag). I have all the events logged, so it shows me every event that occurs.</p>
  
  <p>Here's a simplified version of what I'm doing:</p>
  
  <pre><code>import pyglet
  
  window = pyglet.window.Window(width=640, height=480)
  window.push_handlers(pyglet.window.event.WindowEventLogger())
  
  label = pyglet.text.Label("Hello world", font_name="Times New Roman" ,
                            font_size=36, x=window.width // 2, y=window.height // 2, 
                            anchor_x="center, anchor_y="center")
  @window.event
  def on_mouse_press(x,y,button,mod):
      print("Button Pressed")
  
  pyglet.app.run()
  </code></pre>
  
  <p>My version is python 3.6. I'm using the PyCharm IDE (I've also tested it through cmd), Pyglet 1.3.1, and I'm using Windows 10</p>