mxConnectionHandler.prototype.start=function(a,b,c,d){this.previous=a;this.first=new mxPoint(b,c);this.edgeState=null!=d?d:this.createEdgeState(null);this.marker.currentColor=this.marker.validColor;this.marker.markedState=a;this.marker.mark();this.fireEvent(new mxEventObject(mxEvent.START,"state",this.previous))};mxConnectionHandler.prototype.isConnecting=function(){return null!=this.first&&null!=this.shape};mxConnectionHandler.prototype.isValidSource=function(a,b){return this.graph.isValidSource(a)};