At the bottom of a lister files/dirs are only shown completely. Also there's no smooth scrolling (only row-by-row).
That was changed some time before (showing a half row at the end) to see if the list continues, but doesn't work here on two computers.
Are they running Opus 8 or something? Partial lines at the bottom were added in Opus 9 as I remember.
(Probably obvious but just in case: Make sure you're not looking at a List mode display, too. They obviously won't show partial lines since anything that won't fit will end up in the next column.)
How things scroll depends on both the machine's mouse driver settings and whether Opus's scroll acceleration is enabled (in Prefs / Advanced / Misc.).
Solved, I changed the height of the toolbar, half rows are now shown.