message: expose pause rendering to main window
diff: @@ -81,6 +81,7 @@ static ImGuiWindowFlags g_imguiWindowFlags = ImGuiWindowFlags_AlwaysAutoResize;
  static bool g_quitNextFrame = false;
  static bool g_saveNextFrame = false;
  static bool g_animatingPath = false;
  +static bool g_pauseRendering = false;
  static const std::vector<std::string> g_scenes = {"empty",
  "multilevel_hierarchy",
  @@ -566,6 +567,9 @@ void MainWindow::keyboardMotion()
  void MainWindow::motion(const vec2f &position)
  {
  + if (g_pauseRendering)
  + return;
  +
  const vec2f mouse(position.x, position.y);
  if (previousMouse != vec2f(-1)) {
  const bool leftDown =
  @@ -612,6 +616,9 @@ void MainWindow::motion(const vec2f &position)
  void MainWindow::mouseButton(const vec2f &position)
  {
  + if (g_pauseRendering)
  + return;
  +
  if (glfwGetMouseButton(glfwWindow, GLFW_MOUSE_BUTTON_LEFT) == GLFW_PRESS
  || glfwGetMouseButton(glfwWindow, GLFW_MOUSE_BUTTON_MIDDLE) == GLFW_PRESS
  || glfwGetMouseButton(glfwWindow, GLFW_MOUSE_BUTTON_RIGHT) == GLFW_PRESS)
  @@ -806,8 +813,12 @@ void MainWindow::waitOnOSPRayFrame()
  void MainWindow::updateTitleBar()
  {
  std::stringstream windowTitle;
  - windowTitle << "OSPRay Studio: " << std::setprecision(3) << latestFPS
  - << " fps";
  + windowTitle << "OSPRay Studio: ";
  +
  + if (g_pauseRendering) {
  + windowTitle << "rendering paused";
  + } else {
  + windowTitle << std::setprecision(3) << latestFPS << " fps";
  if (latestFPS < 2.f) {
  float progress = frame->frameProgress();
  windowTitle << " | ";
  @@ -823,6 +834,8 @@ void MainWindow::updateTitleBar()
  progBar.back() = ']';
  windowTitle << progBar;
  }
  + }
  +
  glfwSetWindowTitle(glfwWindow, windowTitle.str().c_str());
  }
  @@ -1374,6 +1387,8 @@ void MainWindow::buildMainMenuEdit()
  void MainWindow::buildMainMenuView()
  {
  if (ImGui::BeginMenu("View")) {
  + if (ImGui::Checkbox("Pause rendering", &g_pauseRendering))
  + frame->pauseRendering = g_pauseRendering;
  if (ImGui::MenuItem("Screenshot", "s", nullptr))
  g_saveNextFrame = true;
  if (ImGui::MenuItem("Keyframes...", "", nullptr))
  