title: Paste Event in a WPF TextBox
body: <p>I have created a custom control inheriting <code>TextBox</code>. This custom control is a numeric <code>TextBox</code>, only supporting numbers.</p>
  
  <p>I am using <code>OnPreviewTextInput</code> to check each new character being typed to see if the character is a valid input. This works great. However, if I paste the text into the <code>TextBox</code>, <code>OnPreviewTextInput</code> is not fired.</p>
  
  <p>What is the best way to capture pasted text in a <code>TextBox</code>?</p>
  
  <p>Also, I have a problem when the back space is pressed, I can't figure out what event this will fire. <code>OnPreviewTextInput</code> is not fired!</p>
  
  <p>Any ideas how to capture pasted text and back space events in WPF <code>TextBox</code>?</p>