The problem with mouse wheel scrolling in the stats area was a side effect of the changes in 3.9.0: They added that you can click on a stat and a tool tip pops up that describes the effect. That brought a very old bug into the scrolling of the stats area:
Mouse wheel scrolling does not work when the mouse pointer is over a clickable area! It seems that the mouse wheel messages are grabbed by the clickable area, but then ignored and dropped instead of passed on to the underlying scrollable area.
For example, in the stats area, mouse wheel scrolling does not work in the red shaded areas, because they can be clicked. However, the scrollable area itself is slightly bigger, so mouse wheel scrolling still works in the green shaded area:
Same applies to the inventory, where horizontal mouse wheel scrolling works only between (!) the items:
At least you can place the cursor in the gap between the top and bottom row to do the scrolling.
However, in the chest selection, where vertical (!) mouse wheel scrolling only works in the green shaded areas above / below the chest, it is effectively unusable: