message: make resolution scaling selections from the 'App' menu
diff: @@ -563,14 +563,37 @@ namespace ospray {
  if (ImGui::Checkbox("Interaction Cancels Frame",
  &cancelFrameOnInteraction));
  - if (ImGui::DragFloat("Render Resolution Scale", &renderResolutionScale,
  - .01f, 0.01f, 4.f)) {
  + ImGui::Separator();
  +
  + if (ImGui::BeginMenu("Scale Resolution")) {
  + float scale = renderResolutionScale;
  + if (ImGui::MenuItem("0.25x")) renderResolutionScale = 0.25f;
  + if (ImGui::MenuItem("0.50x")) renderResolutionScale = 0.5f;
  + if (ImGui::MenuItem("0.75x")) renderResolutionScale = 0.75f;
  +
  + ImGui::Separator();
  +
  + if (ImGui::MenuItem("1.00x")) renderResolutionScale = 1.f;
  +
  + ImGui::Separator();
  +
  + if (ImGui::MenuItem("1.25x")) renderResolutionScale = 1.25f;
  + if (ImGui::MenuItem("2.00x")) renderResolutionScale = 2.0f;
  + if (ImGui::MenuItem("4.00x")) renderResolutionScale = 4.0f;
  +
  + if (scale != renderResolutionScale)
  reshape(windowSize);
  +
  + ImGui::EndMenu();
  }
  + ImGui::Separator();
  +
  if (ImGui::MenuItem("Take Screenshot"))
  saveScreenshot = true;
  + ImGui::Separator();
  +
  if (ImGui::MenuItem("Quit")) {
  renderEngine.stop();
  std::exit(0);
  