It is good practice to not make the expanded combobox larger than the dialog itself. CBS_NOINTEGRALHEIGHT will allow to set a fixed amount of pixels for the v6 combobox, and therefore allows us to hide the problem for this specific dialog. The problem was unhidden by 0.4.12-dev-882-g e3e173ffaafbccb0e9b52926d41626d5a4dc38cd Even after this patch I think Wines comctl32 can be improved for comboboxes with very many elements that do not use this small trick yet. I will create a follow-up-ticket.