ThemeViewer is a tool that gives you the ability to preview a custom or a predefined theme for all controls of the suite. To access the Theme Viewer simply click on the Windows Start button and type "Theme Viewer". It can be started from the Live Demo under Featured Applications as well. If you are not able to find the Live Demos using that approach you can also download it directly from here.
The controls are placed on different pages which can be selected from the left panel and some controls are placed on separate forms in order to be displayed correctly.
Switching between the different themes and loading custom themes is available from the drop down button on the top of the form:
Additionally, you have the opportunity to change a variety of settings that concern the theming of the controls, such as RightToLeft, Disabled and Aero mode.