tk4.2 User Commands - tkwait






NAME

     tkwait - Wait for variable to change or window  to  be  des-
     troyed


SYNOPSIS

     tkwait variable name

     tkwait visibility name

     tkwait window name





DESCRIPTION

     The tkwait command waits for one of several things  to  hap-
     pen,  then it returns without taking any other actions.  The
     return value is always an empty string.  If the first  argu-
     ment is variable (or any abbreviation of it) then the second
     argument is the name of a global variable  and  the  command
     waits  for that variable to be modified.  If the first argu-
     ment is visibility (or any  abbreviation  of  it)  then  the
     second  argument is the name of a window and the tkwait com-
     mand waits for a change in its visibility  state  (as  indi-
     cated  by  the  arrival  of a VisibilityNotify event).  This
     form is typically used to wait for a newly-created window to
     appear  on  the  screen  before  taking some action.  If the
     first argument is window (or any abbreviation  of  it)  then
     the  second  argument is the name of a window and the tkwait
     command waits for that window to be destroyed.  This form is
     typically used to wait for a user to finish interacting with
     a dialog box before using the result of that interaction.

     While the tkwait command is waiting it processes  events  in
     the  normal  fashion,  so  the  application will continue to
     respond to user interactions.  If an event  handler  invokes
     tkwait again, the nested call to tkwait must complete before
     the outer call can complete.



KEYWORDS

     variable, visibility, wait, window