Mike, New exception: efiring@manini:~/programs/py/mpl/tests$ python ../matplotlib_units/unit/memleak_gui.py -dwx -s1000 -e2000 > ~/temp/memleak_wx_0705.asc Traceback (most recent call last): File "../matplotlib_units/unit/memleak_gui.py", line 58, in <module> pylab.close(fig) File "/usr/local/lib/python2.5/site-packages/matplotlib/pylab.py", line 742, in close _pylab_helpers.Gcf.destroy(manager.num) File "/usr/local/lib/python2.5/site-packages/matplotlib/_pylab_helpers.py", line 28, in destroy figManager.destroy() File "/usr/local/lib/python2.5/site-packages/matplotlib/backends/backend_wx.py", line 1405, in destroy self.frame.Destroy() File "/usr/local/lib/python2.5/site-packages/matplotlib/backends/backend_wx.py", line 1364, in Destroy wxapp.Yield() AttributeError: 'listiterator' object has no attribute 'Yield' Eric