axes.set_xticklabels bug?

simple pylab script:

a = axes()
a.set_xticklabels(['a', 'b', 'c'])

When I move the mouse around the axes I get this error from the callback:

/usr/local/lib/python2.4/site-packages/matplotlib/ in
__call__(self, x, pos)
    176 'Return the format for tick val x at position pos'
    177 if pos>=len(self.seq): return ''
--> 178 else: return self.seq[pos]
    180 class FuncFormatter(Formatter):

TypeError: list indices must be integers

"pos" is None

Any ideas?
- Charlie

CVS and at least GTKAgg and TkAgg