message: Clearing scene now re-adds the default dark gray background
diff: @@ -39,7 +39,7 @@ bool LightsManager::addLight(NodePtr light)
  if (light->subType() == "hdri" || light->subType() == "sunSky") {
  auto &frame = parents().front();
  auto &renderer = frame->childAs<sg::Renderer>("renderer");
  - renderer["backgroundColor"] = vec4f(vec3f(0.f), 1.f); // black, opaque
  + renderer["backgroundColor"] = rgba(vec3f(0.f), 1.f); // black, opaque
  }
  lightNames.push_back(light->name());
  @@ -80,8 +80,11 @@ void LightsManager::clear()
  removeLight(name);
  }
  - // Re-add the default-ambient light, when clearing all others
  + // Re-add the default-ambient light and gray background, when clearing lights
  addLight("default-ambient", "ambient");
  + auto &frame = parents().front();
  + auto &renderer = frame->childAs<sg::Renderer>("renderer");
  + renderer["backgroundColor"] = rgba(vec3f(0.1f), 1.f); // Near black
  }
  void LightsManager::preCommit()
  