Drop-down boxes will go off the top of the screen if they cannot "fit" onto the screen either up or down. For example, on the Mozilla bug submission form, if the OS box is vertically located approximately at the middle of the screen, then at 800x600 resolution (and presumable lower) the box will drop-down towards the top of the screen, and the top of it will be cut off by the upper edge of the screen. (This is really hard to describe -- would you like a screenshot?)
Reassigning to Rod.
setting milestone to M15
fixed for very general cases/
I verify the fix on windows 98.
Updating QA contact.
Verified Build 2001080603 os:win98