but a different aspect ratio, 16:9, and the image is correctly displayed. Could it be it?
That's a very plausible explanation, yes: If you feed the monitor 16:9, but it has a 16:10 panel, it may really do the worst thing you could possibly do, and that's crop the picture to fill the whole screen. It wouldn't be the first time that a decision made by the monitor on it's own (attempting to be more clever than the user) is about the dumbest thing you can think of
So a future update of the config tool, which hopefully finds a 16:10 mode in the next level of EDID blocks, might fix it. We have an internal version of the core that hopefully solves the VSync polarity problem (still need to hook up measurement equipment and see if we *really* solved it). Also, reading out the "deeper" EDID levels is also something that's on the agenda for the next version of the config tool - please give us a bit more time to do finalize and polish these. We've already pushed our luck by doing releases in very fast succession, but we should go back to more structured work.