Y.Base.build(..)
Y.SliderBase
min
max
Converts a pixel position into a value. Calculates current * thumb offset from the leading edge of the rail multiplied by the * ratio of (max - min) / (constraining dim).
(max - min) / (constraining dim)
Override this if you want to use a different value mapping * algorithm.
_offsetToValue( xy )
valueChange
value