Not sure if this is really a bug/oversight or just a poor design decision but I've noticed whenever there's enemies off screen with an arrow appearing at the edge to indicate them if I try to scroll the screen over there and the mouse touches one of the arrows, the scrolling stops. This is really annoying in the later maps that have lots of enemies you need to scroll over to see and I'd much rather the screen just kept scrolling if I touch the arrows.
That's a very awkward way of doing it IMO. If the screen is already scrolling it should just keep scrolling even if I hover over the arrows since it makes scrolling in the later levels really annoying.