Vista Sidebar's main window displaying the actual sidebar and the gadgets that you can open on it. 

Vista Sidebar's main window showing the available clock formats and the possible skins for the sidebar. The activated skin visible in the picture is Curved. 

The Preferences tab in the Properties window lets you customize the application according to your needs and preferences. 

The Appearance tab allows you to tweak the application's look and feel through the available settings: Z-Order, Opacity, Shadow, Hue Shift and Accessibility.