   func draw() {
     link.color.set()
     constructArrow()?.bezierPath().fill()
+    drawSelectedRing()
     drawLinkText()
   }
   

    let results = document.concepts.filter { (concept) -> Bool in
      return concept.rect.contains(clickedPoint)
    }
    guard results.count > 0 else { return nil }
    return results
  }

    let point = convertToCanvasCoordinates(point: event.locationInWindow)
    
    if event.isSingleClick() {
      if let clickedElements = clickedElements(atPoint: point) {
        Swift.print("[mouseDown][singleClick] clicked concepts [\(clickedConcepts)]")
        
        if (!currentState.isSimilar(to: .multipleSelectedElements(elements: [Element]()))) {
          safeTransiton {
            try stateManager.toSelectedElement(element: clickedElements.first!)
          }
        }
        
