[gwbas1c]

It's called MSI, and it's been in Windows for 20 years.

The issue is that MSI is very buggy when handling explorer extensions. If you're not careful, when you uninstall it'll prompt you to close explorer.

(I know because I shipped a product that installed via MSI and had an explorer plugin. The installer issues were more complicated than the plugin.)

In this case, the issue is that when explorer loads a plugin, it keeps an open file handle to the dll. This gives the installer two options: Restart explorer.exe, or somehow finish uninstalling when explorer.exe terminates.

The product that I shipped just restarted explorer.exe.