Also define utilities that manipulate layers.
| Function | setAdditionalLayer | Undocumented |
| Function | setFirstLayer | Undocumented |
| Interface | LaunchpadLayer | The LaunchpadLayer layer. |
| Interface | DebugLayer | The DebugLayer layer. |
| Interface | APIDocLayer | The APIDocLayer layer. |
| Interface | TestOpenIDLayer | The TestOpenIDLayer layer. |
| Class | PageTestLayer | The PageTestLayer layer. (need to register a 404 view for this and |
| Interface | FeedsLayer | The FeedsLayer Layer. |
| Interface | WebServiceLayer | The layer for web service requests. |