Mon Sep 20 12:51:30 EDT 1999  Austin Donnelly  <austin@gimp.org>

	Honest, guv, it's not a feature - it's a tightly integrated
	package of undo system cleanups and fixes.

	NEW FILES:
	* app/undo_history.c: window showing recent undo (and redo) steps
	    available.
	* app/undo_types.h: broken out of undo.h to fix circular includes.

	MODIFIED FILES:
	* app/Makefile.am: compile undo_history.c
	* app/channel.h: use enum for channel undo type, not just magic
	    numbers.
	* app/layer.h: same for layer undos.
	* app/commands.c: edit_show_undo_history_cmd_callback() function to
	    pull up undo history window.
	* app/commands.h: prototype for above.
	* app/gdisplay.c: make undo / redo menu items sensitive according
	    to whether they would do anything.  Would be easy to change
	    the text to say what would be undone/redone, but I don't know
	    the GTK.
	* app/gimpimage.c: new signal emitted by gimage:
	    UNDO_EVENT. gimp_image_un...