Sergey,
>I wouldn't rely on grid thumb because most of the time VFP doesn't place it correctly anyway.
My experience matches your comment that VFP does not seem to position a thumb accurately or consistently.
> Is additional info current row related?
The additional info is based on the row that would be selected if the record pointer was moved to the approximate position reflected by the thumb.
Perhaps I should use an ActiveX scrollbar and manage it myself from the grid? I'm not excited about this option, but I suspect its either this approach or the approach of using to a form's Point method in a loop, scanning for a pattern that matches the edge of a thumb?
Regards,
Malcolm