See http://www.pmview.com/forum/index.php?showtopic=443 for similar problem, that has the relevant screenshot.
(I thought I'd posted about this at the same time I posted about the other, OS/2-specific problem, but I see that I didn't.)
In Win, using the mouse I can use the control arrow on the right to display the history list.
With the entry area in focus, I can use the <CurDn> to scroll through history one item at a time.
However, what I can't do is <Alt+CurDn> to display the list, as I can with the mouse and the right control, or as I can using <Alt+CurDn> in the OS/2 version.