code: function (placeholder, _jsPlumb, ipco, ips) {
  		var n = jsPlumb.createElement("div", { position : "absolute" });
  		_jsPlumb.appendElement(n);
  		var id = _jsPlumb.getId(n);
  		jsPlumb.setPosition(n, ipco);
  		n.style.width = ips[0] + "px";
  		n.style.height = ips[1] + "px";
  		_jsPlumb.manage(id, n, true); // TRANSIENT MANAGE
  		// create and assign an id, and initialize the offset.
  		placeholder.id = id;
  		placeholder.element = n;
  	}
docs: creates a placeholder div for dragging purposes, adds it, and pre-computes its offset.