problem with Axes3D.cla

Hello list,

I encounter a problem with the method Axes3D.cla.
I'm running the follwing lines in "ipython -pylab"

from mpl_toolkits.mplot3d import Axes3D
fig = plt.figure()
ax = Axes3D(fig)

Then I do have a Axes3D, in which I can perform zooming with left and right
mouse button. If I now call


to clear the axes the screen is freezed and I don't know how to leave this
state enabling again zooming.

Thanks in advance for any hints.

Kind regards,