src/lib/mouse_event_point.js
function mouseEventPoint(mouseEvent, container) {
  const rect = container.getBoundingClientRect();
  return new Point(
    mouseEvent.clientX - rect.left - (container.clientLeft || 0),
    mouseEvent.clientY - rect.top - (container.clientTop || 0)
  );
}
function mouseEventPoint(mouseEvent, container) {
  const rect = container.getBoundingClientRect();
  return new Point(
    mouseEvent.clientX - rect.left - (container.clientLeft || 0),
    mouseEvent.clientY - rect.top - (container.clientTop || 0)
  );
}
function mouseEventPoint ( mouseEvent , container ) { const rect = container . getBoundingClientRect ( ) ; return new Point ( mouseEvent . clientX - rect . left - ( container . clientLeft || 0 ) , mouseEvent . clientY - rect . top - ( container . clientTop || 0 ) ) ; }
Returns a Point representing a mouse event's position
relative to a containing element.

@param {MouseEvent} mouseEvent
@param {Node} container
@returns {Point}
Returns a Point representing a mouse event s position relative to a containing element .