We don't use skycolor by default because we render a skybox. Backbuffer shouldn't depend on it. Also current backbuffer can't be access it's failed to acquire.
If someone has a wish to customize a background color. The easiest and cross-platform way is to make a skybox with a needed color: create a folder art/textures/skies/green and make 5 images with same color in that folder: back.png, front.png, left.png, right.png and top.png.