OpenDarwin 7.2.1 - man page for update (opendarwin section n)

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

_________________________________________________________________________________________________

NAME
       update - Process pending events and idle callbacks

SYNOPSIS
       update ?idletasks?
_________________________________________________________________

DESCRIPTION
       This  command  is  used to bring the application ``up to date'' by entering the event loop
       repeatedly until all pending events (including idle callbacks) have been processed.

       If the idletasks keyword is specified as an argument to the command, then no new events or
       errors  are  processed;	only idle callbacks 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.  Most display updates are performed as
       idle callbacks, 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 triggered by window size
       changes; these updates will not occur in update idletasks.

       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 events such as user
       interactions;  if you occasionally call update then user input will  be	processed  during
       the next call to update.

SEE ALSO
       after(n), bgerror(n)

KEYWORDS
       event, flush, handler, idle, update

Tcl					       7.5					update(n)