I wonder if someone else suggested this before. Can't find the idea here so I might just as well suggest it:
An option to zoom into/out of the source code would be more than helpful.
One screen is most often too small, scrolling (even if you keep it horizontally) moves parts of the code away and the small zoom window doesn't allow editing.
Even if you never ever write ugly spaghetti code that uses more than one screen - that bloody guy who messed up the job before you had to fix the VI did so. ;-)
We usually work on 1280x1024 screens but our machines sometimes only have 800x600 - guess what happenes...
regards,
Sören