REBOL [title: "List Widget Demo"]

y: read %.
c: 0
x: copy []
foreach i y [append/only x reduce [(c: c + 1) i (size? to-file i)]]

slider-pos: 0
view layout [
    across space 0
    the-list: list 400x400 [
        across space 0
        text 50 purple
        text 250 bold [editor read to-file face/text]
        text 100 red italic
        return box green 400x1
    ] supply [
        count: count + slider-pos
        if none? q: pick x count [face/text: none exit]
        face/text: pick q index
    ]
    slider 16x400 [
        slider-pos: (length? x) * value
        show the-list
    ]
]