Hm, I see what you're doing now. This works but I still think wheels could just get the current value and add. If there is a different connection to the wheel event than the mouse click event then you will mix the mouse click event's value with the wheel event. 

In most cases these will be the same, but if the skinner chooses (in the future) the wheel event may be connected to something different. We would of course never do this in our release skins but a user may want to do this.