[Cin]Lock position of any source contents within track

Considering the following use case. You have an ISO (multi cam) recording from an Atem device. To redo the switching in post. I know Cinelerra supports the multi cam option. But I am looking for something else. In essence I want to say to the content of these tracks, this is the time code from 0 must never ever move the on the timeline, not accidentally, everything is locked. The only operations that are allowed: - mute - move a split/cut forward backward (but not the movement when it is before the content, I think this happens with middle mouse) I think this time line lock is useful for many editing operations, like you are tweaking any keyframes. It is a different part of editing. -- Stefan