code: function addPathHandle($canvas, parent, xProp, yProp) {
  
  	var handle = $.extend({
  		cursors: {
  			mouseover: 'grab',
  			mousedown: 'grabbing',
  			mouseup: 'grab'
  		}
  	}, parent.handle, {
  		// Define constant properties for handle
  		layer: true,
  		draggable: true,
  		x: parent[xProp],
  		y: parent[yProp],
  		_parent: parent,
  		_xProp: xProp,
  		_yProp: yProp,
  		fromCenter: true,
  		// Adjust line path when dragging a handle
  		dragstart: function (layer) {
  			$(this).triggerLayerEvent(layer._parent, 'handlestart');
  		},
  		drag: function (layer) {
  			var parent = layer._parent;
  			parent[layer._xProp] = layer.x - parent.x;
  			parent[layer._yProp] = layer.y - parent.y;
  			updatePathGuides(parent);
  			$(this).triggerLayerEvent(parent, 'handlemove');
  		},
  		dragstop: function (layer) {
  			$(this).triggerLayerEvent(layer._parent, 'handlestop');
  		},
  		dragcancel: function (layer) {
  			$(this).triggerLayerEvent(layer._parent, 'handlecancel');
  		}
  	});
  	$canvas.draw(handle);
  	// Add handle to parent layer's list of handles
  	parent._handles.push($canvas.getLayer(-1));
  }
docs: Add a single handle to line path