docs: public void addChildObjectToCamera(final Widget child, int camera) {
          switch (camera) {
              case LEFT_CAMERA:
                  mLeftCameraRootWidget.addChild(child);
                  break;
              case RIGHT_CAMERA:
                  mRightCameraRootWidget.addChild(child);
                  break;
              default:
                  mMainCameraRootWidget.addChild(child);
                  break;
          }
      }