title: WIX - Verify that file exists - and/or file-browser dialog/button
body: <p>How do you create a "Browse" button in a WIX dialog. </p>
  
  <p>I currently have a custom dialog box with four radio buttons (Dev, QA, Stage, and Prod), and a text field for a filename.  </p>
  
  <p>The install of course dies if the user enters a bad filename. 
  I would be happy first of all just to verify that the file they entered exists.  </p>
  
  <p>Secondly, I would like to add a File-Browser button, if such things exists in WIX.  But even then, I would imagine the user could type in any file name, and I should still check to see if it exists. </p>
  
  <p>Thanks, </p>
  
  <p>Neal Walters </p>