title: Detect MSI package upgrade from bundle
body: <p>I'm looking to move from InstallShield LE to Wix.</p>
  
  <p>InstallShield generates and Foobar.Exe file. I've ran it with /b argument and then used dark.exe to generate wxs code.</p>
  
  <p>I've created an MSI package (Foobar.msi) with the same upgrade code and a Bundle with a Chain with some prerequisites and the Foobar.msi and DIsplayInternaUI=true. The upgrade from InstallShield to Wix works as expected.</p>
  
  <p>However, I'd like the Bundle to handle all UI, like <a href="http://robmensching.com/blog/posts/2012/6/25/b-is-for-bundle-and-thats-good-enough-for-me/" rel="nofollow">Rob Mensching recommends</a> (currently I have two). How can the Bundle know the MSI is being upgraded? Because I need to show some dialogs only on first install (various system settings).</p>