The new non Native Scrollbar in ZK 7+ hides the last part of the Listbox.
Example:
http://zkfiddle.org/sample/1927qt/4-Listbox-scrollbar-hides-last-column

This is aseptically a problem when the last column is just eg. an option menu icon. This could not really be selected with the new Scrollbar.
And even if not, on small listboxes it hides the ending of the values that are listed.