I think this is probably a feature quest as I can't think of a good way to implement this with existing tools.
I want to make eyes (or something else in other scenario) to move toward a bone target but have the distance not going outside of the eye holes to make things looks right. I can only think of a "distance constraint" that cap the distance from the eye center (of course with scaling support to match the oval shape). Any suggestion with creative way to make it work with current tools are welcome 8)
P.S.the things that my character will look at is moving dynamically on the screen that's why I want to have a moving bone to determine where the eyes should look at instead of hard coding how the eyes moves.