In WPF, Binding Between a UserControl and an Application

Question

Hi,

 

I realize a WPF application under VS 2017 Community. I start in this technique. I added a UserControl to the solution and I integrated it into the application. But I can not achieve the binding of a UserControl object (Background) to the same property of an identical object of the main application.

 

In the application, there is a Border named "Feu" which must receive the Border Background also named "Feu" which is located in the UserControl.

 

Who can help me ? thank you very much

 

Here is the source code of solution.