Feature Request: Min Max MIDDLE for sliders

Hey CA gurus,

I would like to request that you add a thrid point on sliders in the controls panel. There should be a middle value as well.

For example, a slider with a MIN and MAX value of -100, but a middle value of 0, so that from left to right, the slider goes -100 up to 0 when it reaches the middle, and then goes back down to -100 as it moves the rest of the way to the right.

For example, I want an eye pupil to feel three dimensional, like it's on the surface of a sphere, so I may have one slider that determines the X position, and another that determines the X scale. It'd be great if the scale was 100% when the eye was in the MIDDLE, but decreased some as the eye went left OR right.

This way, I could have one grouped continuous controller for eye X position that automatically changed the X scael as well to mimic the pupil going across the surface of a sphere.

It'd be even better if we could do advanced rigging options when grouping controls, but if that is too much, just having a middle position value would be amazing.

Thanks.