Usage: WINDOW NOTIFY_LEVEL <l>  
  Where <l> is the same as for LEVEL, this controls what types of 
  messages trigger STATUS_NOTIFY.

  NOTIFY_LEVEL understands BEEP as a level.  Any beep occurring in
  the window will trigger STATUS_NOTIFY.

See also:
  SET LASTLOG_LEVEL for a complete description of the LEVEL parameters.
  SET NOTIFY_LEVEL
  SET STATUS_NOTIFY
  WINDOW
  WINDOW HIDE
  WINDOW SWAP
  WINDOW SHOW