2001-03-04  Michael Natterer  <mitch@gimp.org>

	* app/Makefile.am
	* app/apptypes.h
	* app/gimplayerlistitem.[ch]: new widget derived from
	GimpDrawableListItem (additionally displays the layer mask),

	* app/gimplistitem.[ch]: added the preview_size to the struct so
	subclasses can create previews at arbitrary times. Removed the
	"preview_size" parameter from "set_viewable".

	* app/gimpimage.[ch]: removed the layer mask functions because
	they belong to GimpLayer.

	* app/gimplayer.[ch]: folded the layer mask code from GimpImage
	into GimpLayer's layer mask functions. Added a "mask_changed"
	signal which is emitted when a mask is added/removed. Added
	"push_undo" parameters to the functions so we can use them from
	the undo system.

	* app/undo.c: instead of badly poking the GimpLayer struct, use
	the accessors with push_undo = FALSE.

	* app/gimage_mask.c
	* app/gimpdrawablelistitem.c
	* app/layers_dialog.c
	* app/xcf.c
	* app/pdb/image_cmds.c
	* tools/pdbgen/pdb/image.pdb: changed accordingly.