MainViewport, ScalingViewport, ViewportManager and the viewport CVars should, in my opinion, be moved to the engine.
Right now, OpenDream, a personal project and SS14 all have the same viewport code implementation in content, when it could all be in engine.
Now, it should still be 100 % for content to implement its own special viewport, but in this case this implementation is widely used enough that it should be in engine.
Description
MainViewport, ScalingViewport, ViewportManager and the viewport CVars should, in my opinion, be moved to the engine. Right now, OpenDream, a personal project and SS14 all have the same viewport code implementation in content, when it could all be in engine. Now, it should still be 100 % for content to implement its own special viewport, but in this case this implementation is widely used enough that it should be in engine.