title: matplotlib: how to constrain mouse event handling to top-most artist?
body: <p>I am looking for a method  in matplotlib to create multiple interactive artists (i.e. rectangles, circles, etc) in a single axis that can be resized/rotated/moved using the mouse. I successfully tried <a href="http://matplotlib.org/users/event_handling.html#draggable-rectangle-exercise" rel="nofollow">this example</a> to create a "draggable" rectangle in matplotlib. However, when two such draggable rectangles overlap, both will move and not just the top-most one as I would like. How can I make sure that only the top-most artist under the mouse pointer will respond to mouse events?</p>