2000-12-28  Sven Neumann  <sven@gimp.org>

	* app/channel.c
	* app/layer.c: use gtk_object_sink() instead of gtk_object_unref()
	when deleting a layer or channel since only floating objects should
	be destroyed this way. A layer or channel that has been attached
	to an image shall never be deleted.

	* app/layer_cmds.c
	* libgimp/gimplayer_pdb.c
	* tools/pdbgen/pdb/layer.pdb: reenabled the gimp_layer_delete() PDB
	function since it might be useful under rare circumstances.