title: textbox only for integer in window application
body: <p>I have a Windows application, in which there is a login form and registration form.
  In the registration form there are 4 <code>textbox</code>es in which one of them is for getting the user contact number (Mobile Number), where only numbers are allowed.
  I want that user can enter only <code>integer</code> number not <code>char</code> just like in <code>asp</code> application, where using <code>ajax</code> textfilter we restrict the user to enter only integer number. </p>
  
  <p>Does this type of functionality exist, such that the Windows application can restrict the user?</p>