Rose Edit: Properly document widgets

[wxtim]

The only reference I can find to the assorted widgets in the documentation are here. They do not reference all of the widgets.

Perhaps we could create documention like that for

rose/lib/python/rose/config_editor/valuewidget/choice.py

Line 35 in 2c8956a

class ChoicesValueWidget(gtk.HBox):

and use that with Sphinx autodocumentation?