Color scheme Teal is not working properly in Forms 12c

Our Forms application used the color scheme Teal for years now. In that scheme the canvas can be green of light grey (tab pages). The prompts are black in green pages and black on grey pages. We are migrating from Forms 10g to 12c, and we see that the colors are different. A stacked canvas on top of a tab page becomes green instead of grey. Prompts on a green canvas are black instead of white (except for check boxes, which have white prompts), making them difficult to read. Is this a bug and can we expect a fix?