title: Write special masked TextBox for WPF
body: <p>I want to develop a custom user control in WPF which has some sort of mask. this functionality is very like the one provided in many online applications where u enter your credit card number and next time whenever u sign in to your account u see only last for digits of the card number (something like <strong>**</strong>*4587) but while I display data in this way I want to keep real value unchanged so inside binding I will access full data.</p>