Proposed GtkTreeView API change

[Jonathan Blandford <jrb redhat com>]

Currently GtkTreeView has a "range_changed" signal on it that is
supposed to let the view know when a series of rows change.  It was
added when signals were slower, and sizing of rows was different.
Unfortunately, since then row sizing has changed such that you need to
walk the range anyway, and you emit a bunch of signals per row (a
"property_notify" per column).  Additionally, none of the models emit
it, and the TreeView doesn't support it.  Changing GtkTreeModelSort to
support it will be a nightmare.  All this leads me to believe that we
need to change it to be just "changed" (or maybe "row_changed").  I'd
like to do this, though it will break anyone's code who's using this or
writing their own model.  Comments??

Thanks,
-Jonathan