7. Add a material to the object
Properties Menu >> Materials tab >> New
8. Set to object material to Shadeless
Properties Menu >> Materials tab >> Shading tab >> Shadeless checkbox
- The Overlay Scene doesn't have a light. Setting the material to shadeless will let us see the object.
9. Switch back to the main scene
- Info menu >> Scene box list >> Select main scene
- The overlay scene is added in the main scene.