As I said in the forums, I vote for something like #4 + #3 + #1
LEFT and RIGHT apply setting wherever the current selection is, unless a setting was already applied with SELECT, and leave the screen. STOP leaves the screen and doesn't apply a setting. SELECT applies the setting where the cursor is but stays in the screen. A tick mark shows what setting is currently applied. So that you can see what you would have when you cancel out or what you have set with SELECT. To give more visual feedback on the selection, there could be a small "animation" when you leave the screen with LEFT or RIGHT: if you press the button, the tick mark jumps to the selected setting and the screen is shown for about half a second (or less), then it backs out. This delay should be made configurable (and turn-off-able). I don't like LEFT and RIGHT to behave differently, a new user wouldn't find it intuitive that one is cancel and one is apply. Without an annoying splash screen he might never find out which is which. Like I said in the forums, I never use Cancel and if I would want to use it, I would expect STOP to behave as a cancel button. I'm confusing LEFT and RIGHT all the time anyway ;-) -- Rincewind
