This example combines features of earlier examples: it allows to enter an address via a mask, and a push button causes the entered data to be appended to a text in a file. Afterwards, the entered data is cleared again. In order to be able to notify controls of a change in the displayed data, the interactor must be an extension of a Dialog.Interactor. For this purpose, there is the Dialog.Update procedure which takes an interactor as parameter. After one or possibly several calls to Dialog.Update, procedure Dialog.CheckGuards should be called. This gives the controls the opportunity to evaluate so-called guard procedures, which may enable or disable controls, depending on the new state of the interactor.