SceneViewport UpdateCachedGeometry only run on mouse events

Currently, UpdateCachedGeometry is only called for mouse events over the scene viewport. This leads to issues with trying to project a point between the world space and screen space during PIE if the mouse is not over the game viewport (like when running an Automation Test).

Adding a call to UpdateCachedGeometry to OnDrawViewport fixes this, but I’m not sure if this is good for performance.

I think Tick would be a better place than OnDraw. This method is trival so it should not affect perf. We will take a look.

This issue has been fixed in 4.8.
The Tick now receives the Geomety so it updates the CachedGeometry now, this fix is not a performance issue where as calling UpdateCachedGeometry() would have been relatively expensive by comparison.