Q:

strange IDE in Visual Studio

In my VS2015 there is a strange HTML tree nodes view of my MVC View.  This tree nodes view occupies 1/4 of the screen all the time.  I don't know what addon I added.  There is no way to dismiss it.  Does any know?

A:

I solved the problem by disable the suspected add-on one at a time until the problem goes away.  Interestingly, when I re-enable each of the disabled add-on, the problem goes away without removing any add-on.

