Can't create items in context menu in WPF editor

Question

I've made a context menu in WPF for my TabItem. But for some reason, it won't allow me to add items to it. I was hoping to pop up a box with options like, close, rename, etc. I've got the Items collection, just everything's greyed out. I'm quite new to WPF and C# so feel free to point out the obvious. I'm in Visual Studio 2010.

Answer 1

I inserted stuff manually into the XAML and it accepted it without problems. Not funny, but not a big deal.