Options found so far:
-1-
use Scitech Display Doctor 7 Beta. Nice but (relatively) slow. License expires after 21 days. Hint: remove it from the Start menu for faster booting.
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use svga.exe and 'vgapatch p' as suggested for Win 3.1. Original post:
http://forums.virtualbox.org/viewtopic.php?t=1033
Go for 1024*768*256. Not perfect either but faster and no nagging about a license. Main problem : terribly slow when it comes to shutdown so I kill the machine when all done and accept the resulting scandisk at next boot..... O and there's something about DOS boxes but you have a somewhat similar problem in Win 3.x with this solution.
Note: you can install svga under Win 98 SE but the resulting VM has lost some of its stability, in addition to the quirks above.