I've recently added an instance of the Slider class to my layout. (The vertical slider, from Taharez lnf)
But if my mouse is over it and I scroll with the mouse wheel, it seems to scroll the opposite way to what I expected. If I scroll up (away from me), the slider thumb goes to the bottom (and getCurrentValue reports zero). Scrolling down moves the slider thumb to the top.
For comparison, mouse wheel scrolling works the way I expected in a MultiColumnList.
Additional information: This issue was created from the following forum thread: http://www.cegui.org.uk/phpBB2/viewtopic.php?t=3626