2001-01-26  Havoc Pennington  <hp@redhat.com>

	* gtk/gtktreemodel.c, gtk/gtktreemodel.h: add GtkTreeRowReference
	which holds a handle to a specific row (particular set of values
	in the model, i.e. pointer-identity row).

	* gtk/gtktreeview.c, gtk/gtktreeprivate.h, gtk/gtktreeselection.c:
	use GtkTreeRowReference for anchor, cursor, and drag_dest_row.
	Still need to use it for the src/dest row saved on the drag context.