diff --git a/examples/drag-and-drop/drag-and-drop-2.rkt b/examples/drag-and-drop/drag-and-drop-2.rkt
index 84e3b3f..70b603f 100644
--- a/examples/drag-and-drop/drag-and-drop-2.rkt
+++ b/examples/drag-and-drop/drag-and-drop-2.rkt
@@ -79,6 +79,7 @@
 ;; Mouse handling.
 
 ;; When the mouse is down, select the shape being clicked.
+;; The shape being mousedowned is the one with focus.
 (define (mousedown w v evt)
   (define selected-shape (find-shape (world-shapes w) (view-id v)))
   (make-world (remove selected-shape (world-shapes w))