Currently it is not possible to select another item in a combobox via mouse wheel.
Combobox Item should be able to be changed via mouse wheel.
Normally in windows it is possible to move the mouse over a combobox and then scroll with the mouse wheel to select another item.
You can try this for example in windows explorer options.
Open FFF Settings (Edit Process Settings)
Move mouse to combobox "Auto-Configure for Material" and scroll mouse wheel - nothing happens.