synchronized h-scrolling?

[Kalle Olavi Niemitalo]

I've been editing some ASCII-art tables where the first few lines
are headers and the rest are data, like this:

Motherboard       Chipset    CPU  Shape
================= ========== ==== =====
Abit KT7          VIA KT133  D/TB ATX
Abit KT7-100 Raid VIA KT133  D/TB ATX
Abit KT7A         VIA KT133A D/TB ATX

The real table was much longer, and when I edited the bottom
lines, the header lines scrolled out of sight.  To prevent that,
I split the window vertically and adjusted the upper window to
show only the header.  So far so good.

However, the table was also wider than the screen, and when I
scrolled the bottom window horizontally (with auto-show-mode and
truncate-lines), the upper window stayed still and the headers
didn't match the data at all.

In the end, I worked around the problem by using a single window
and making some intervening lines invisible, but that was rather
cumbersome.  Is there a mode which would have scrolled both
windows?