Enable and disable a button box based on input.
So I have a button box in a modal window, with two column selection boxes above it. The math later on could break if the two columns are the same, so I don't want the user to be able to click the same columns. I assume the simplest way to do this is to disable the button box until conditions are satisfied (both column selector boxes have a selection and don't have the same (assuming there are more...