##
slider.setMoveFunc()

    function f(s) {
        var v = s.getValue()
        // do something with v, the current value of slider s1 or s2
    }
    var s1 = new slider
    var s2 = new slider
    s1.setMoveFunc(f)
    s2.setMoveFunc(f)

Sets the function that is called when the slider button is moved. The first parameter to the function is the slider object that triggered it. This slider's "getValue()" method gives the actual value of the slider when it did the function call. Note that this function is only called when the slider button is dragged, not when it moves by clicking somewhere else in the slider.