Can you implement this, because that could speed up building an UI dramatically and one is not limited for only colors.
Do you want something as a watermark? in all your forms (I do not understand the foreground thing in your suggestion)
Now we are limited for colors in backgrounds. I want to choose a picture as a background.
Foregrounds: For example: A progress bar is filled with the foreground color, I would like to fill a progress bar with a picture, or to fill the lines of a rectangle with a picture.