


update(n)              Tk Built-In Commands             update(n)


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

SYNOPSIS
       (update)

       (update 'idletasks)


DESCRIPTION
       This  procedure  is  used to bring the entire application world ``up to
       date.''  It flushes all pending output to the display,  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 pending
       when-idle handlers, no pending output to the server, and no  operations
       still outstanding at the server.

       If  the  idletasks option is specified as an argument to the procedure,
       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 immedi-
       ately.

       The  update idletasks procedure 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.  Most display updates are performed as idle  handlers,  so
       update idletasks will cause them to run.  However, there are some kinds
       of updates that only happen in response to events, such as those  trig-
       gered  by  window  size changes; these updates will not occur in update
       idletasks.

       The update procedure with no options is useful in scripts where you are
       performing  a  long-running computation but you still want the applica-
       tion to respond to user interactions;  if you occasionally call  update
       then user input will be processed during the next call to update.




















STk                            3.1                              1


