2003-03-17  Michael Natterer  <mitch@gimp.org>

	Made drawable/layer properties (visibility, opacity etc.)
	undoable (fixes bug #73893).

	* app/core/core-enums.[ch]: added undo types/groups for
	visibility, mode, opacity, linked and preserve_trans.

	* app/core/Makefile.am
	* app/core/core-types.h
	* app/core/gimpitemundo.[ch]: new GimpUndo subclass which holds a
	ref'ed GimpItem pointer so (1) this doesn't need to be done by all
	undo steps related to an item and (2) the item the undo step is
	for can be determined from outside the undo system.

	* app/core/gimpimage-undo.[ch]: added gimp_image_undo_push_item()
	which returns a new GimpItemUndo.

	* app/core/gimpimage-undo-push.[ch]: use it for all item related
	undo steps. Removed lots of GimpItem, GimpLayer, GimpDrawable
	and GimpVectors pointers from the private undo structs. Added
	undo push functions for the new undo types added above.

	* app/core/gimpdrawable.[ch] (gimp_drawable_set_visible): added
	"gboolean push_undo" parameter.

	* app/core/gimplayer.[ch] (gimp_layer_set_opacity, _mode,
	_preserve_trans, _linked): added "gboolean push_undo" parameters.

	* app/core/gimpimage-mask.c
	* app/core/gimpimage-merge.c
	* app/core/gimplayer-floating-sel.c
	* app/tools/gimpmovetool.c
	* app/xcf/xcf-load.c
	* app/widgets/gimpdrawablelistitem.c
	* app/widgets/gimplayerlistitem.c
	* app/widgets/gimplayerlistview.c: changed accordingly.

	* tools/pdbgen/pdb/channel.pdb
	* tools/pdbgen/pdb/layer.pdb: ditto. Added '$undo' paramaters to
	the foo_accessors() functions. Removed $func from foo_accesors()
	because we don't manipulate items without using getters/setters
	any longer.

	* app/pdb/channel_cmds.c
	* app/pdb/layer_cmds.c: regenerated.

	* app/widgets/gimpcellrenderertoggle.[ch]: added "clicked" signal
	which carries an additional "GdkModifierType state" parameter as
	in GimpCellRendererViewable .

	* app/widgets/gimpcontainertreeview.c: emit "clicked" from
	the toggle renderer, not "toggled" so the callbacks get the
	modifier state.

	* app/widgets/gimpdrawabletreeview.c: resurrected the "exclusive
	visible by <shift>+click" feature as in 1.2.

	* app/widgets/gimplayertreeview.c: compress layer opacity undos by
	looking at the top of the undo stack and not pushing an undo if
	there already is a GIMP_UNDO_DRAWABLE_OPACITY for the active
	layer.