Originally posted by Michael Babin
The problem with that approach is that the slider provides a continuous setting from Low to High, but the Auto setting is a discrete setting. What would the values of the slider between High and Auto mean? If you made the slider continuous between Low and High, and then jump to Auto once the mouse was moved far enough, the effect would be quite jarring, IMHO.
Correct, it should snap into place for "Auto".
There is MUCH precedent in user interface design for this, such as dimmer switches with sliders.