2001-05-31  Dave Neary  <dneary@eircom.net>

	* app/core/gimpimage.[ch]
	* app/core/gimpimage-mask.c
	* app/tools/gimpbycolorselecttool.c
	* app/undo.c: Added a "mask_changed" signal, to allow
	gimpbycolorselect to update it's dialog properly, and take out a
	silly dependency in gimpimage.

	One outstanding issue is that now the dialog doesn't close
	automatically when the tool context changes. Working on it :)