The goal of the xfce4-quicklauncher-plugin is double.
First, it is intented to offer you a fast and easy way to configure the
plugins wich are on your panel.
Secondly, it is able to display these launchers on one or more lines, and
they are displayed so that they don't waste space. They also feature
a little zoom effect when you pass the mouse over them.


WWW: http://goodies.xfce.org/projects/panel-plugins/xfce4-quicklauncher-plugin