A parameter value _starts_ being changed due to an UI element.
Called when a widget that can changes this parameter is mouseover, and wants to signal that to the listeners.
Called when a parameter value _stops_ being changed.
Called when a widget that can changes this parameter is mouseover, and wants to signal that to the listeners.
A parameter value was changed, from the UI or the host (automation).
Parameter listeners are called whenever: - a parameter is changed, - a parameter starts/stops being edited, - a parameter starts/stops being hovered by mouse
Most common use case is for UI controls repaints (the setDirtyXXX calls)