Recently @wsengsiry-20 asked a question about "same activity getting edited by multiple people at same time" and in the end the last person who saves activity will keep his work and others will lose their work.
I guess this would be great feature if target locks perticular activity if someone else is working on it currently.
Maybe this can be achieved in two ways,
1. Lock an activity for all other people if someone else is working on it.
2. Show popup "someone else is currently editing this activity" if I'm trying to edit an activity on which someone else is working.
