Instant notification of which sentences are currently being worked on by other users?
I'd like to avoid reduplication of effort, along with the embarassment/bad manners of replacing one perfectly good translation with another perfectly good one that differs only slightly a few minutes later. I think it would be great if whether a sentence is being worked on by another user were somehow visible in the text and updated in realtime. For example, the sentence could be given a light-colored background or outline and the username of the editor(s) could be displayed when hovering over it.
Even better would be if the text itself were updated live as those other users save their edits.