message: Add shift-ctrl-leftMouse only sets focusDistance, without changing center
diff: @@ -544,6 +544,7 @@ void MainWindow::pickCenterOfRotation(float x, float y)
  y = 1.f - clamp(y / windowSize.y, 0.f, 1.f);
  res = fb.handle().pick(r, c, w, x, y);
  if (res.hasHit) {
  + if (!glfwGetKey(glfwWindow, GLFW_KEY_LEFT_CONTROL) == GLFW_PRESS)
  arcballCamera->setCenter(vec3f(res.worldPosition));
  auto &camera = frame->child("camera");
  camera["lookAt"] = vec3f(res.worldPosition);
  