title: wix custom dialog for config edit
body: <p>hi i'm trying make a setup msi for my application with wix v3
  I have a problem about this task;
  I need a user input that will be stored in my application's config file
  (for example i need a dialog for sql connection string and the user input will be written in application config file.)</p>
  
  <p>I tried to google but got nothing worked</p>
  
  <p>Any help is greatly appreciated.</p>