Comment by kampopat

OP here. It's actually a single mode. Since the view doesn't have a horizontal scroll, the selection is activated as soon as you slide your finger horizontally and will continue (horizontal or vertical) until you lift your finger. Of course this means that only the visible cells on screen can be selected in one go before you'd have to release (it will keep the selection) and then scroll down before selecting another group. Hope that clears it up!