function changeClass(x) {

    if ( x.className == "selected" ) {
	return;
    }

    if ( x.className == "off" ) {
	x.className = "on";
    }
    else if ( x.className == "on" ) {
	x.className = "off";
    }
    else {
	x.className = "on";
    }
}

$(document).ready(function () {

    /* Install the header buttons mouse over event handlers */
    $('#buttons img').each(
	function() {
	    $(this).bind( 'mouseover', function() {changeClass(this) } );
	    $(this).bind( 'mouseout',  function() {changeClass(this) } );
	}
    );

});