WPF + MVVM and WinForms folder dialog, how to manage them?

Since Folder dialog is not supported in WPF out of box, we have to use WinForms dialog.
But how to use it with MVVM pattern?

Here one small tip.

Behavior and usage

One bad side is that property name is string. But good part, no view code behind.

Here is link to gist where you can find view, viewmodel and behavior
https://gist.github.com/odugen/ae2d790cea26f01ea0e7