gnome-control-center/capplets/screensaver/screensavers/blitspin.xml

<?xml version="1.0" encoding="ISO-8859-1"?>

<screensaver name="blitspin">

    <command arg="-root"/>

    <number label="Speed of rotation." low-label="Faster" id="delay"
            type="slider" default="2" arg="-delay %" low="1"
            high-label="Slower" high="500000"/>

    <number label="Speed of the 90 degree rotation."
            low-label="Faster" id="delay2" type="slider"
            default="5000" arg="-delay2 %" low="1" high-label="Slower"
            high="500000"/>

    <boolean label="Display screensaver in monochrome." arg-unset=""
             id="monochrome" test="mono" arg-set="-mono"/>

</screensaver>