This is fixed now in SVN. The problem was that Numeric arrays lack a
"len" attribute, and "hasattr(xmin, 'len')" was being used to find out
whether xmin is a scalar or a length-2 array (xmin, xmax). The solution
is to do the test with "iterable(xmin)" instead. The bug was introduced
in 2782.
John,
It seems that ScalarMappable in cm.py, Artist in artist.py, and Button
in widgets.py all have quite similar observer functionality, with some
variable and method names in common and some not. None of this
functionality seems to be used very extensively (a conclusion based only
on a litt
