Open new Window from ViewModel in WPF MVVM

Rav! Srivastava. CodeProject. 2016-10-02.
Implementing Factory design pattern to open new Window from ViewModel in WPF MVVM.
I got several question posted on web “How to open new window from view model in MVVM pattern” and I have also encountered the same problem  at beginner level  after googling and learning design pattern got the solution of this problem  and  decided to write an article with deep discussion. In this article we are going to implement the Factory Design Pattern. It will provide a flexible and loosely coupled environment.

[Open new Window from ViewModel in WPF MVVM]