For the purposes of focusing the viewer's attention on overlaid titling or overlaid transparent images, it would be cool to be able to darken and gaussian blur any part of a video clip or image on the timeline. (the idea is to have the darkening/blurring options available from the Callout menu ... but without having to create a callout.) What would be ideal is if the blur effect was a separate track on the timeline that would blur all layers beneath it. But that seems like it might be challenging.