I got this error while using matplotlib 1.0.1 on OS X 10.6.6.

Traceback (most recent call last):
File "python2.7/site-packages/matplotlib/backend_bases.py", line 1625, in motion_notify_event
self.callbacks.process(s, event)
File "python2.7/site-packages/matplotlib/cbook.py", line 265, in process
proxy(_args, *_kwargs)
File "python2.7/site-packages/matplotlib/cbook.py", line 191, in call
return mtd(_args, *_kwargs)
File "python2.7/site-packages/matplotlib/backend_bases.py", line 2573, in drag_zoom
self.draw_rubberband(event, x, y, lastx, lasty)
File "python2.7/site-packages/matplotlib/backends/backend_macosx.py", line 420, in draw_rubberband
self.canvas.set_rubberband(x0, y0, x1, y1)
TypeError: integer argument expected, got float