Probably the best way to handle this then is for the Windows menu code
to replace _ in menu item text with &, and for mac, tmm and
non-toolkit X menu code to strip out the _ (or build the code in to
handle it). Then we can go through our menus and add _'s as
appropriate.
Menus are often consed together from various modules. I don't think
that this would work reliably. I think it would be better when the
abbreviations would be chosen automatically in most cases. Even
though it might make sense if the automatisms would try to obey
suggestions where possible.