Hi Jim,
There is no code at all in any of the methods (of the second listbox, the one that is subclassed directly from the VFP base class)..
I've been working on this problem for so long that I may be missing the forest for the trees. I know this is not a bug in VFP because I have another listbox in another app that is set up the same way and works properly. There's something strange going on here--over the weekend I came up with the idea that there may be a problem with how the control interacts with the page frame on the form. I will turn on coverage just before I click on the listbox and see what happens.
What seems so strange to me is the fact that the top two rows of the listbox are not selectable, or perhaps it is that only the bottom two rows are selectable. I never heard of any behavior like this in VFP. That's why I think there may be a bug involved, although clearly the bug does not manifest all the time.
I'll test the coverage and I could also test event tracking. Will let you know what I find.
Thanks, Chaim