treeeitem and forall

[Owen Taylor <otaylor redhat com>]

The behavior of gtk_widget_show_all() for tree items changed
in a somewhat odd way between 1.0.x and the current CVS,
apparently because of:

	* gtk/gtktreeitem.c: provide a _forall implementation,
	which walks the subtrees as well for include_internals.

gtk_widget_foreach() on treeitems used to to include the
subtree unconditionally, so show_all() would walk the
entire tree and expand everything. 

This is pretty much what I would expect, because the
subtree isn't an "internal" - it is a added by the
user explicitly. 

I'm not really sure what show_all() should do, but forall()
seems like it should include the subtrees, and since show_all()
used to include the trees, I don't think it would hurt
if it continued to do so... 

Regards,
                                        Owen