OnGUI() not called during DragAndDrop

I have a custom editor window that needs some drag and drop functionality. For some reason, the window stops repainting once dragging starts. Since OnGUI stops, dragging can never complete.

What the test window looks like:

Test Code:

     public class DragTest : EditorWindow
     {
         [MenuItem("Window/Drag Test")]
         internal static void Init()
         {
             GetWindow(typeof(DragTest), false, "Drag Test");
         }
 
         private List<Draggable> draggables;
 
         public DragTest()
         {
             draggables = new List<Draggable>();
 
             for (int i = 0; i < 10; i++)
                 draggables.Add(new Draggable(i));
         }
 
         private void OnGUI()
         {
             Debug.Log("On GUI");
 
             // update each draggable
             foreach (Draggable draggable in draggables)
                 draggable.Draw();
         }
     }
 
     public class Draggable
     {
 
         private int number;
 
         public Draggable(int number)
         {
             this.number = number;
         }
 
         public void Draw()
         {
             EditorGUILayout.LabelField("Draggable Object");
 
             // get area that can be clicked on
             Rect dropArea = GUILayoutUtility.GetLastRect();
 
             Event currentEvent = Event.current;
 
             // ignore if mouse is outside the area
             if (!dropArea.Contains(currentEvent.mousePosition))
                 return;
 
             switch (Event.current.type)
             {
                 case EventType.MouseDown:
                     Debug.Log("Clicked on " + number);
 
                     // no more OnGUI messages after this
                     DragAndDrop.PrepareStartDrag();
 
                     currentEvent.Use();
                     break;
 
                 case EventType.MouseDrag:
                     Debug.Log("Dragging" + number);
                     DragAndDrop.StartDrag("Title");
 
                     currentEvent.Use();
                     break;
 
                 case EventType.DragUpdated:
 
                     Debug.Log("Drag updated on " + number);
 
                     currentEvent.Use();
                     break;
             }
         }
     }