2003-05-21  Michael Natterer  <mitch@gimp.org>

	* app/core/gimpdrawable.[ch]: added GimpDrawable::alpha_changed()
	signal.

	* app/core/gimpimage-undo-push.c
	* app/core/gimplayer.c: emit it when alpha is removed from or
	added to a layer.

	* app/widgets/gimpcontainertreeview.[ch]: added a
	"name_attributes" column to the list store which provides a
	PangoAttrList for the name column.

	* app/widgets/gimplayertreeview.[ch]: connect to all layers'
	"alpha_changed" and set the BG layer's name to bold.

	* app/widgets/gimpdrawabletreeview.c: removed redundant assertions.