API suggestion

add/remove methods ? Or is the (recently changed)

    > collections attribute the Right Way (TM) to do this kind of
    > thing ?

Yes, I you're doing it the right way. I decided to make these
attributes "public" when working on the figures for the "Matplotlib
API" chapter of the users guide, eg Figure 7.4, which shows the Artist
containment hierarchy and the respective attribute names.


I've historically been reluctant to publicize the API in order to
leave wiggle room for refactoring the internals, but now I'm
reasonably satisfied and the API has been mostly stable for several
releases. The choice to remove the underscore on these attribute
names was an unheralded decision that the basic API / containment
hierarchy is stable for the foreseeable future.

You can safely use the list remove method w/o breaking anything. If
you want to manually add an artist to the Axes, you should use the
Axes add_patch, add_line, add_collection, etc, methods rather than the
list append method, unless you really know what you are doing. These
add_* methods set some default attributes of the artist, eg they call
the set_figure, set_transform, and update the data limits for viewport
autoscaling. So you either need to use the add_* methods to add
artists or call these methods yourself.