I decided to add this and work on it tonight. Already, you can scroll horizontally by using Alt+Wheel. The GUI toolkit provides inbuilt vertical and horizontal scroll by wheel for the ScrollView component I am using, and I cannot change its shortcuts. I added Ctrl+ for horizontal zoom, but I cannot get it to work in all areas! The ScrollView steals the mouse wheel for places where there is no track.
I made Shift+ adjust the track height. You can hold both Ctrl & Shift at the same time to zoom both horizontal and vertical at the same time.