Scatter plots and GTK backend


I am having trouble viewing scatter plots of large data sets
with the GTK backend. The plots are sparsity patterns of
sparse matrices, much in the way of Matlab's spy function.
First of all, there may be a conflict somewhere with my
version of GTK/PyGTK; issuing a plot() or scatter() command
often results in the message 'None Active' being displayed.
After a couple of seconds, the python prompt comes back, and
the 'scatter' command results in a huge number of messages
of the form

    <matplotlib.patches.Circle instance at 0x4531730c>

begin displayed; litterally hundreds of them---it takes some
10 seconds. Finally, a show() opens up a Figure window, but
no plot. The matrix has 80519 nonzero elements and is
symmetric, so the scatter plot contains roughly twice as
many points. I have a Gnuplot interface and a spy-like
function which works just fine and displays the pattern in a
matter of a fraction of a second.

Sometimes, a plot using the GTK backend gets stuck in
gtk.mainloop(), and i have to interrupt it with Ctrl-C. I am
using SuSE Linux 8.0. I have installed the most recent
versions of GTK and PyGTK.

Thanks in advance for any suggestions.