So are you trying to have two vertical headers? I don't want to seem stubborn or condescending if you are already using a header, but if you aren't using one, adding a vertical header will give you what you want - something that stays in place even when scrolling.

Someone correct me if I'm wrong, but I think in order to freeze a column in place (other than the header) when scrolling, you might need to dig into the Qt source and make some changes.