WPF has no concept of MDI applications. In fact Microsoft is trying to discourage any one using that form of application. I'm new to WPF and I really like MDI applications. It allows me to move quickly between windows and compare the content of different windows. Furthermore, sometime the content of one window is useful for another so I can copy and paste. I think it's a great user experience for working mode. To continue, download the attachment! It includes two folders, they are very simple code. The point is how you can terminate an application (Windows Form and WPF).