how NOT to "focus_out" of an entry ?

[David Pirotte]

Hello,
        
i need to force the user to stay in a particular entry, if and while
the entry does not vlideta a condition, for exemple a valid string
date format

i tried the following, but was unsuccessfull, the system does not
stay on the entry that i wish ot would, the one the user was trying
to get out:


        ;; just for the example
        (define (str-valid-dte? date-str)
          #f)
        
        (gtk-signal-connect entry "focus_out_event"
                            (lambda (a)
                              (let ((date-str (gtk-entry-get-text entry)))
                                (if (str-valid-dte? date-str)
                                    #t
                                    (begin
                                      (system "beep")
==> is this the correct way?          (gtk-widget-grab-focus entry)
                                      )))))
thanks
david