Hide vertical scroll in listbox?

On ListBoxes, the vertical scroll bar disables but does not disappear when it's unneeded. I am wondering if anyone is aware of a way to hide the vertical scroll bar in these situations (or even in all situations)? Alternatively, can the size of the scroll bar be modified? I've tried to read the documentation carefully, and I haven't come up with anything. Attached is an example of panel which I could make smaller if the scroll bars were hidden. Increasing the overlap between the panels does not help matters -- vertical scroll bars always seem to be on top, no matter the relative front/back ordering of the listboxes.

(The reason that this particular example panel has 6 listboxes instead of 1 listbox with a wave of 6 columns is that the number of items listed in each listbox may sometimes vary.)

Thanks in any case!