For Silverlight version of the control, forces C1MaskedTextBox to update its Value and Text properties when the control is not loaded. Does nothing in WPF.
In Silverlight, when C1MaskedTextBox is not loaded yet or not included in a visual tree at all, it doesn't get notifications about the Text property changes and can't update its Value and Text properties at the proper time therefore, this behavior is inherited from the base TextBox control. If you need to get correct values of these properties while the control is not loaded, call the UpdateValue method after you changed the properties that affect a text formatting, such as Mask, TextMaskFormat and so on.
This method does nothing when Silverlight version of the control is loaded, as well as in the WPF version of the control at any moment independently of its load state.