2004-01-18  Michael Natterer  <mitch@gimp.org>

	* app/core/gimpimage.c (gimp_image_set_active_layer): don't allow
	to select anything but the floating selection. Fixes bug #128025.

	(gimp_image_set_active_layer,channel,vectors): allow to pass NULL
	to unselect the active item. Removed the silly feature that
	passing some random item of another image would select the first
	item in the list (was unused anyway).

	(gimp_image_unset_active_channel): use gimp_image_set_active_channel()
	now that it accepts NULL.

	(gimp_image_add_layer,channel,vectors): cleaned up / simplified.

	(gimp_image_remove_layer,channel,vectors): cleanup,
	simplification, use gimp_image_set_active_layer,channel,vectors()
	now that they accept NULL, make sure the item next to the removed
	item becomes the active one (and not the first in the list, which
	was a severe usability problem in the dialogs).

	* app/core/gimpimage-undo-push.c (undo_pop_layer,channel): pas...