message: Minor: Adding object requires ctrl + click
diff: @@ -70,6 +70,9 @@ export namespace ThreejsAddSimpleObject {
  const canvas = mapView.canvas;
  canvas.addEventListener("mousedown", event => {
  + if (!event.ctrlKey) {
  + return;
  + }
  // snippet:harp_gl_threejs_add_simple_object_1.ts
  // Get the position of the mouse in world space.
  const worldPositionAtMouse = mapView.getWorldPositionAt(event.pageX, event.pageY);
  @@ -106,7 +109,7 @@ export namespace ThreejsAddSimpleObject {
  }
  const message = document.createElement("div");
  - message.innerHTML = `Click to add a ${scale}m wide cube to scene.`;
  + message.innerHTML = `Ctrl + click to add a ${scale}m wide cube to scene.`;
  message.style.position = "absolute";
  message.style.cssFloat = "right";
  