NAME
       update - Process pending events and/or when-idle handlers

SYNOPSIS
       update ?idletasks?


DESCRIPTION
       This command is used to bring the entire application world
       ``up to date.''  It flushes all pending output to the dis-
       play,   waits  for  the  server to process that output and
       return errors or events, handles all pending events of any
       sort  (including when-idle handlers), and repeats this set
       of operations until there are no pending events, no  pend-
       ing  when-idle  handlers, no pending output to the server,
       and no operations still outstanding at the server.

       If the idletasks keyword is specified as  an  argument  to
       the  command,  then no new events or errors are processed;
       only when-idle idlers are invoked.  This causes operations
       that  are  normally  deferred, such as display updates and
       window layout calculations, to be performed immediately.

       The update idletasks command is useful  in  scripts  where
       changes  have been made to the application's state and you
       want those changes to appear on the  display  immediately,
       rather  than  waiting  for  the  script  to complete.  The
       update command with no options is useful in scripts  where
       you  are  performing  a  long-running  computation but you
       still want the application to  respond  to  user  interac-
       tions;   if  you  occasionally call update then user input
       will be processed during the next call to update.


KEYWORDS
       event, flush, handler, idle, update
