title: NumberField prompt in ExtJS
body: <p>I'm trying to show a MessageBox.prompt with a numberfield instead of a regular textfield.
  I couldn't go around creating a new MessageBox so I decided to just use a validator instead, but I'm having some trouble with it too.</p>
  
  <p>So anything will work for me, either a number validator for a MessageBox or a MessageBox with a numberfield instead of textfield.</p>
  
  <p>Here's my MessageBox...</p>
  
  <pre><code>var msgbox = Ext.Msg.prompt('Quantity', 'Enter a number',function(btn, text){} )
  </code></pre>
  
  <p>Any ideas for this?</p>
  
  <p><strong>UPDATE</strong></p>
  
  <p>I managed to get the validator working, but I would much rather have a numberfield instead of a textfield, so the first part of the question is still up.</p>
  
  <p>How do I get to show a numberfield instead of a textfield on a MessageBox.prompt on ExtJS.</p>