Strange black box appearing in wpf application

Question

Hi!

I am new in wpf application development. I just create a demo application and I see that the black box appearing in the top of my application. Can anyon

Answer 1

This is a new feature as of VS 2015 Update 2 XAML Diagnostics. This shows up only if you are debugging the application.

If you really need to disable this, there's an option in the Tools > Options > Debugging > General - Enable UI Debugging Tools for XAML > Show runtime tools in application