No you can't, the sorting algorithm when specifying the s switch is alphabetically, and we want to sort numerically.
//window -s @@ | aline @@ 20 | aline @@ 5 | aline @@ 30
You'd have to start padding all numbers to an arbitrarily long enough length using $base, which will result in a sort from lowest to highest value.
And why would you choose a listbox? It offers no extra functionality in this case over a sorted regular window.
Sorry, no dice.
