Launch dialog on uninstall using WiX

I have created a WiX installer and would开发者_如何学Python like to launch a custom action dialog on uninstall. From this dialog I would like to gather information on why the user is uninstalling my application (well, this means just launching the web-browser).

I have seen some people using the On="uninstall" property, but I am not sure if this is the one to use, and how to use it, for the above action.

Windows doesn't show UI when a product is uninstalled from Add/Remove Programs or Programs and Features.

JakobJ: I wouldn't mess with this uninstall sequence. Any modal dialog that pops up when the installation is run in silent mode (which it is from add/remove) could cause your entire product to be axed in a corporate environment. If your uninstall is invoked from a management system such as SCCM and the uninstall on a lot of machines fails because the uninstall gets stuck on a dialog, this will not soon be forgotten. Trust me.