You probably want to look at customizing the VScrollBar.mouseWheelHandler() method. Attached is a sample of how to do that.
If you would like an easier way of doing this please file an enhancement request at http://bugs.adobe.com/flex
Thank you very much for your helpfull answer.
It works like a charm.
I tried the same with a HSlider but my knowledge is still to less to be able to overwrite the mouseWheelHandler.
This seems not to be working with the HSlider?
override mx_internal function mouseWheelHandler(event:MouseEvent):void
For deeper understanding, is there somewhere a tutorial how to approch those kind of thinks ?
How to find those function? Where do I get this 'mx_internal' ?
How do I find the mouseWheelHandler of the <s:HSlider?
If I have understood that once it would be much easier.
Thank you very much
An alternative solution is to subclass Group and override theIViewport method getVerticalScrollPositionDelta to return a pre-set step size, then use that subclass as the viewport for your scroller. Much simpler than mucking about with the scrollbar implementation! Full details in this post right here: http://forums.adobe.com/message/3844410#3844410
I just saw in the GroupBase that it takes the value of it's layout's getVerticalScrollPositionDelta method. So you could just extend BasicLayout and override that method which would be a bit cleaner and more future proof I think