I don't know if there's a button to do that, but I have noticed the following:
I have an option selected, but want to scroll the list of options down or up. I scroll the mouse wheel, figuring that will move the list. If the option currently selected has a list associated with it, it will be shifted one entry down (or up) and then the selected option will change to the next one down in the list, regardless of which way I scrolled the mouse wheel.
This causes annoying problems, like trying to output code in apt_format, turning coolant off, etc. I've adopted a strict rule of "look at all the options again before hitting OK" to prevent maddening errors.
