How do you add an item to the "Open With" dialog that opens from Solution Explorer's "Open With..." context menu.

Hi, I need to add an item from a VS Extension to the "Open With..." dialog that appears in VS 2015 when you click on the Solution Explorer's "Open With..." context menu.

I've looked though all the availible VS interfaces and cannot find the correct one. I can add the item manualy and every thing works the way I want it to. I just need to be able to add it to this "Open With" list in my Extension.

Many Thanks

Neal