title: Ignore matplotlib cursor widget when toolbar widget selected?
body: <p>I am using a cursor widget in an interactive Matplotlib plot like so:</p>
  
  <pre><code>cursor = Cursor(ax1, useblit=True, color='red', linewidth=1)
  cid = fig.canvas.mpl_connect('button_press_event', on_click)
  </code></pre>
  
  <p>Works well.  The <code>on_click</code> function takes the x,y click locations and does some supplemental plotting.  Basic stuff.</p>
  
  <p>When I activate the zoom tool I am also capturing the click.  Is it necessary to bind an activate and deactivate key stroke to the widget a la the RectangleSelector example or does a method exist that knows the state of the toolbar items?</p>
  
  <p>Example of the selector on/off from the RectangleSelector example:</p>
  
  <pre><code>def toggle_selector(event):
      if event.key in ['Q','q'] and toggle_selector.RS.active:
          toggle_selector.RS.set_active(False)
      if event.key in ['A', 'a'] and not toggle_selector.RS.active:
          toggle_selector.RS.set_active(True)
  </code></pre>