Once you added source
            nodes to your scene, you can access the Source menu to apply various
            settings.
         
         To access the Source menu:
         
         
            - Do one of the following:
               
                  - Select a Matte or Front Source node in
                     the schematic, and then click the Source menu button.
                     NoteIf no source node
                           is selected when first accessing the Source menu, or if there are
                           no source nodes present in the scene, all of the options in the
                           menu are disabled.
                         
- Double-click a Matte or Front Source
                     node in the schematic.