[Bug] History view infinite scroll can't keep up

[Meshiest]

The history view's infinite scroller stops fetching rows (and emitting onScroll) when you reach the top before the prevPage request finishes

When the prevPage does finish, the scroll position (on the top) is retained rather than going back to where the message was. Probably need some kind of relative positioning for the previous first line and append the difference in heights to the top of the scroller on load.