Actions and callbacks to handle edit boxes allow you to get the current value and know when focus is lost.
However, because characters in edit boxes are already visible, there is no need for action on interim results. Edit boxes only return a callback code when the focus to that tile is lost. The following code example checks the value but does not redisplay it:
(action_tile "myeditbox" "(edit_action $value $reason)") . . . (defun edit_action (val why) (if (or (= why 2) (= why 4)) . ; Do range checking on . ; transient value here. . ) )