renpy screen arrow keys

init:
    $ ax, ay = (.5, .5)
    $ aplus = .01
    transform axy(x, y):
        align(x, y)
    image pers = Text("{size=256}@")
screen test:
    key "focus_left" action SetVariable("ax", ax - aplus)
    key "focus_right" action SetVariable("ax", ax + aplus)
    key "focus_up" action SetVariable("ay", ay - aplus)
    key "focus_down" action SetVariable("ay", ay + aplus)
    add "pers" at axy(ax, ay)

label start:
    centered "Жми кнопки стрелок для управления штруделем.{w=2.0}{nw}"
    show screen test
    pause
    return