I don't figure your concern, to me, the actual layout is just perfect, you see all the pictures and can click directly the one you want, do you mean scrolling on the control without previously clicking on it? Or you mean scrolling with all the pictures shown... Please explain further.
In the same way as you get a choice between how you select a Case Structure case, you can select directly from the Case Selector or scroll through the cases in order with the mouse wheel.