New Post: Close All option for AvalonDock

I can't for the life of me find out how to enable this option. The option to right-click a tab and close all the open documents like you would in Visual Studio. At the moment I can only 'Close' and 'Close All But This'

Any help would be great thanks.

http://stackoverflow.com/questions/26133649/avalondock-2-0-enable-close-all-in-context-menu