Are we talking about the ability to scroll the drop-down list or to change the selection with the mouse wheel?
If we are talking about scrolling, iGrid drop-down list work are standard drop-down lists of combo boxes in Windows and work the same. What you can do with them, you can do in iGrid too. But as we can see from our experience, sometimes operations related to the mouse wheel depend on the mouse and its driver. Not all mouse drivers send the standard WM_MOUSEWHEEL message, and this may cause problems with processing mouse wheel operations.