I use an older version of this bundle in my project where I could append ?&background_color%5Br%5D=255&background_color%5Bg%5D=255&background_color%5Bb%5D=255&foreground_color%5Br%5D=0&foreground_color%5Bg%5D=0&foreground_color%5Bb%5D=0 to the end of the URL to modify the colors.
Is this now no longer possible? Is it on the road map for future development?