function slidePanel(panelID) {
    var panelSelector = "#" + panelID;
    $j(panelSelector).slideToggle('slow', function () {
        var img = $j("img." + panelID)[0];
        var isVisible = $j(panelSelector).is(":visible");
        img.src = isVisible ? "/img/minus_button.gif" : "/img/plus_button.gif";
    });
}