Add support for viewport linked at playtime

Hi there,

I’d love to have the ability to play from a selected viewport(1) and have another viewport(2) update to reflect the running scene. I should then be able to click and drag around an actor in viewport(2) and see that reflected in the viewport(1) that I was playing in.

At the moment, the shadows move in viewport(2), but not the actor geometry. This would be rad :slight_smile: Thanks!