Right now, when I have a file with very long lines, it is less smooth to have to scroll one window, then the other, trying to keep them in sync. It would be useful to have the two windows scroll at the same time. If the other behavior is also useful, just having the ability to set a preference to get the sync behavior would be fine.

In general, I prefer to "zoom" on long lines by right clicking on them.

Syncing horizontal scrolling can be tricky since the line length do not necessarily match up and fractions in the scrollbars' xview can be different. I'm not sure how to solve that smoothly.

In 2.7 more keyboard bindings for scrolling has been added.
This includes left/right for horizontal scrolling which scrolls both windows.