code: function setMarker(element, marker) {
  
      [ MARKER_ATTACH, MARKER_OK, MARKER_NOT_OK, MARKER_NEW_PARENT ].forEach(function(m) {
  
        if (m === marker) {
          canvas.addMarker(element, m);
        } else {
          canvas.removeMarker(element, m);
        }
      });
    }
docs: Sets drop marker on an element.