The current implementation of the viewport list make it really slow and tedious to navigate to the items at the very bottom. In my opinion, there must be two extra arrow icons that allow a quick scroll to 1/4 or 1/2 page with a single mouse click (similar to what the “Page up” and “Page down” keys do in Word and other text editing programs). Or, simply make the existing arrow icons do the same job instead of scrolling line by line. Or, a right-click should scroll 1/4 or 1/2 page. Or, make Rhino take advantage of the “Page up” and “Page down” keys while the viewport list is active.
Or, make it possible to use the mouse scroll wheel to scroll the list up and down. Not sure why this is not the default behaviour, since it’s proven as the best way to scroll menus and pages in nearly all programs since decades, including Rhino’s own “Properties” panel.