I really appreciate the advanced crop feature (crop top, bottom . . .) But I find it very difficult sometimes to crop a video to line up with features on another editing track (e.g., the borders on a slide) using my mouse. Is there a way percentages (e.g., of cropping right) could be adjusted in a very fine-grained way via the keyboard, so, for example, users could specify 'crop right' 8.7%?