Method for starting/ending on subsecond intervals

[Fauntleroy]

On occasion I'll be making a GIF that ends up having a few extra frames from another scene tacked on the end, no matter how careful I am with my start/end times. Ideally there would be some way to crop off extra frames after specifying times, but perhaps some way of specifying intervals shorter than a second would be enough.

I can think of a few different interfaces to fix the issue, but I'm not sure how precise the backend cutting out the clip is.