It would be great to have a property for all visuals wherein you could specify your own "loading" or "refresh" indicator GIF and more importantly an additional checkbox property to give the user the ability to cover the entire visual's width and height with a custom or default dots animation GIF that has a near opaque background. This way, the report consumer very clearly knows it when that visual is being refreshed or loaded. The problem right now I feel is that the dots animation at the top left of every report visual is very small and not easily noticed especially if you have a lot of charts, slicers and other items on your report that are close to each other with customized titles and backgrounds for report visuals.