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

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

<screensaver name="grav">

    <command arg="-root"/>

    <number _label="Number of Colors." _low-label="Colors:" id="colors"
            type="spinbutton" default="200" arg="-ncolors %" low="1"
            high="256"/>

    <number _label="Number of planets to use." _low-label="Count:"
            id="count" type="spinbutton" default="12" arg="-count %"
            low="1" high="50"/>

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

    <boolean _label="Orbit should decay." arg-unset="-no-decay"
             id="decay" arg-set="-decay"/>

    <boolean _label="Objects should leave trails behind them."
             arg-unset="-no-trail" id="trail" arg-set="-trail"/>

</screensaver>