title: Disabling free text in DatePicker TextBox - but allowing delete
body: <p>I've noticed a few posts on here that disable free typing into JQuery DatePicker textboxes,
  e.g.</p>
  
  <pre><code>$("#my_txtbox").attr( 'readOnly' , 'true' );
  
  &lt;input type="text" name="date" readonly="readonly" /&gt;
  
  $("#my_txtbox").keypress(function(event) {event.preventDefault();});
  </code></pre>
  
  <p>But none allow you to delete any dates already populating the textbox. Does anyone know a way of doing this? I also need to maintain the value on postback.</p>
  
  <p>Many thanks</p>