2008-10-14  Michael Natterer  <mitch@gimp.org>

	* app/core/gimpdrawable.[ch]: add a default implementation of
	GimpDrawable::get_node() which contains a layer mode node.
	Implement GimpItem::visibility_changed() and turn the node into a
	nop when the drawable is invisible. Added public function
	gimp_drawable_get_mode_node() so subclasses can plug stuff
	into its "aux" pad.

	* app/core/gimplayer.[ch]
	* app/core/gimpchannel.[ch]: changed accordingly (remove
	duplicated member and code that is now in GimpDrawable).


svn path=/trunk/; revision=27277