title: Is there a way to be notified when an MSI-based installation is starting?
body: <p>I write plugins for a third-party MSI-based product. Unfortunately, because our customizations connect to a database used by this product and also depend on some services of this product, our customizations interfere with upgrading the core software to a newer version. We have looked at the various options for working around this and the easiest would seem to be if we can detect when the upgrade installation starts. Is there a way to be notified when an MSI-based installation is starting?</p>