improve warning.

improve warning.

Fri Oct  5 20:50:00 2001  Jonathan Blandford  <jrb@redhat.com>

	* gtk/gtktreestore.c (gtk_tree_store_iter_has_child): improve
	warning.

	* gtk/gtktreemodel.c (gtk_tree_row_reference_new_proxy): ref and
	unref nodes, #okay61676

	* gtk/gtktreeviewcolumn.c (gtk_tree_view_column_sort): we listen
	to the property; no need to clear the other columns.  Also, we go
	to 'unsorted' if the model supports it.