when scrolling through a conversation and then going to a different conversation for a minute, we need the ability to resume looking at previous conversations at the point we were last looking it it. (example - if I'm scrolling back through 3 months of texts, and I'm at the 1 month back point, just because I leave to do something else for a while doesn't mean I want to have to scroll all the way back to a place I might not remember exactly where it was date wise).