title: Wixsharp External UI (WPF) Installation Path
body: <p>I've been working on external UI for my installer, generated with WixSharp.
  WixSharp samples library has a quite good example on how to create WPF external UI, but I don't understand, how to prompt user to change installation path of my application. Obviously, I have a Setup class, derived from GenericSetup andI can pass a parameter to my MSI file when calling <code>base.StartInstall()</code> method. But how can I get installation directory ftom my MSI to show it for user in a first place?</p>