Optimized camera movement by not repainting the area that was properly moved by the preview. This has several bugs as it stands; it's not an absolute offset, so if we were to move the layer twice before Pixel Store got back to us, we would past the updates on top of each other. Secondly, it does not deal with absolutely positioned elements, such as the red bar standing in for the UI. This last issue should be fixed with the introduction of the layer-to-render-to mechanism.