title: Getting a value before it is changed
body: <p>I am having trouble with getting a value in a text box before the value is changed either by user input or programmatically. </p>
  
  <p>I figure it has to do with the <code>_TextChanged</code> event but once this executes how do I get the old value which was already there before the change?</p>
  
  <p>For example number <code>3</code> is in the text field. The number then changes to <code>4</code> how do I save <code>3</code>?</p>
  
  <p>Thanks in advance!</p>