* app/gimpcontextpreview.c: return without warning if popup_timeout
   is already set. Suppresses warning that occured on double-click.

 * app/layers_dialog.[ch]
 * app/menus.c: added "Delete Mask" menu entry and removed dialog
   asking if mask is to applied or discarded on "Apply Mask".

 * app/tools.c: Magnify is not a transform tool


--Sven