I would really like the ability to scroll with a touchscreen pen or finger when the highlight function is on in Adobe reader. I rarely use the full width of the screen while reading pdf's, and an ideal function for me, when in highlight, would be: when dragging the pen across text, it highlights; when using the pen in the margins of the page, it writes, and when using the pen off the page and along the unused spaces on the sides, it scrolls.
As it is, you need to toggle the highlight function on and off to scroll, which is burdensome. Or you need to use the scroll cursor or up and down arrow keys, which are finicky and difficult to use (especially in long documents). I notice that you can scroll on a touchscreen with two fingers, but I often end up either highlighting anyways or changing the size of the page when trying to use this function, so it does not work for me. Scrolling with two fingers also requires swapping back and forth between fingers and pen, which forces me to flip my wrist and is both clumsy and causes wrist and elbow injuries over time.