So-called 'panelbar' widget.
Creates a panelbar. Its div is accessible as panelbar.div
.
Fading speed can be controlled via fadeDelay.
Adds a new panel, contained in element. It will be shown after clicking on clicker.
Swiches to appropriate panel.
var header = Dom.create("div");
var body = Dom.create("div");
var panelbar = new Panelbar(10);
panelbar.addPanel(header, body);
panelbar.go(0);