Can't resize plot window on Mac

I'm making progress with my little CSV file viewer. I'm doing this
on my Mac, so to make things easier on myself I just installed
the Enthought distribution, avoiding any issues about installing
numpy, matplotlib, etc. As a result I'm using matplotlib 0.99.1.1.

For the minimal gui I decided to just use Tkinter (no gtk in the
Enthought distro apparently). I can select columns to plot, clear
the plot, etc but I can't resize the matplotlib window using the
MacOSX backend. When I roam around the corners of the plot window
or the buttons at the bottom I get error messages like:

    RCNE SendEventToEventTarget (suom 8 ) failed, -9870

When I use the TkAgg backend no plot window appears at all. (I
installed TkAqua. Dunno if that makes a difference.)

Any ideas about how to figure out what's going on?

Thanks,

Skip Montanaro