Set the nocarerefesh flag.  even smart_refresh windows may generate
refresh events if there is a sizing gadget.  If you don't have specific
code to handle this, you must set the NOCAREREFRESH flag.  If you do have
refresh code, be sure to use the begin/endrefresh() calls.  failure to
do one or the other will leave Intuition in an intermediate state, and
slow down operation for all windows on the screen.