message: Add UI framerate rendering stats window
diff: @@ -2205,6 +2205,7 @@ void MainWindow::buildWindowRenderingStats()
  ImGui::Text("renderer: %s", rendererTypeStr.c_str());
  ImGui::Text("framerate: %-5.1f fps", latestFPS);
  + ImGui::Text("ui framerate: %-5.1f fps", ImGui::GetIO().Framerate);
  ImGui::Text("variance : %-5.2f ", variance);
  if (frame->accumLimit > 0) {
  ImGui::Text("accumulation:");
  