message: disable  adjustments to focusDistance for external cameras
diff: @@ -666,7 +666,8 @@ void MainWindow::updateCamera()
  camera->child("direction").setValue(arcballCamera->lookDir());
  camera->child("up").setValue(arcballCamera->upDir());
  - if (camera->hasChild("focusDistance")) {
  + if (camera->hasChild("focusDistance")
  + && !camera->child("cameraId").valueAs<int>()) {
  float focusDistance = rkcommon::math::length(
  camera->child("lookAt").valueAs<vec3f>() - arcballCamera->eyePos());
  if (camera->child("adjustAperture").valueAs<bool>()) {
  