     showTextField(atPoint: concept.point, text: concept.attributedStringValue)
   }
   
-  func transitionedToSelectingElements(fromState: CanvasState) {}
+  func transitionedToSelectingElements(fromState: CanvasState) {
+    commonTransitionBehavior(fromState)
+    
+    // TODO: render the selection rectangle
+  }
   
   private func commonTransitionBehavior(_ fromState: CanvasState) {
     switch fromState {

  }
}

// MARK: - CanvasViewDataSource

extension CanvasViewController: CanvasViewDataSource {


// MARK: - NSTextFieldDelegate

// TODO: handle escape when editing concept

extension CanvasViewController: NSTextFieldDelegate {
  // Invoked when users press keys with predefined bindings in a cell of the specified control.
  func control(_ control: NSControl, textView: NSTextView, doCommandBy commandSelector: Selector) -> Bool {
