Hello, Incremental redisplay uses objects of type output-record to determine what to redisplay. Output records are subclasses of bounding-rectangle. But bounding-rectangle is not a subclass of region, so one cannot use region-intersects-region-p to check whether two output records overlap. But this is in fact the case in the current incremental redisplay code. -- Robert Strandh --------------------------------------------------------------------- Greenspun's Tenth Rule of Programming: any sufficiently complicated C or Fortran program contains an ad hoc informally-specified bug-ridden slow implementation of half of Common Lisp. ---------------------------------------------------------------------