diff --git a/cs621/proj4/KnightsTour.java b/cs621/proj4/KnightsTour.java
index 212c2d1..1d7498c 100644
--- a/cs621/proj4/KnightsTour.java
+++ b/cs621/proj4/KnightsTour.java
@@ -8,6 +8,7 @@ import javax.swing.border.*;
 public class KnightsTour extends JFrame
 {
     private KnightsTourBoard m_ktBoard = new KnightsTourBoard(5, 5);
+    private Thread m_tourThread;
 
     /* GUI elements */
     private ActionEventHandler m_handler = new ActionEventHandler(this);
@@ -16,6 +17,7 @@ public class KnightsTour extends JFrame
     private JTextField m_startXField;
     private JTextField m_startYField;
     private JButton m_startButton;
+    private JButton m_cancelButton;
     private JPanel m_mainPanel;
     private JPanel m_boardPanel;
     private JLabel m_statusLabel;
@@ -67,6 +69,9 @@ public class KnightsTour extends JFrame
                         setLayout(new BoxLayout(this, BoxLayout.Y_AXIS));
                         add(m_startButton = new JButton("Start Knight's Tour"));
                         m_startButton.addActionListener(m_handler);
+                        add(m_cancelButton = new JButton("Cancel Knight's Tour"));
+                        m_cancelButton.addActionListener(m_handler);
+                        m_cancelButton.setVisible(false);
                         add(new Box.Filler(new Dimension(0, 4),
                                            new Dimension(0, 4),
                                            new Dimension(0, 4)));
@@ -91,9 +96,9 @@ public class KnightsTour extends JFrame
         JPanel oldBoardPanel = m_boardPanel;
         m_boardPanel = new JPanel(new GridLayout(height, width, 1, 1));
         m_boardPanel.setBorder(BorderFactory.createEmptyBorder(5, 0, 0, 0));
-        for (int x = 0; x < width; x++)
+        for (int y = 0; y < height; y++)
         {
-            for (int y = 0; y < height; y++)
+            for (int x = 0; x < width; x++)
             {
                 JLabel l = new JLabel(m_ktBoard.getStepAt(x, y) == 0
                         ? ""
@@ -147,9 +152,22 @@ public class KnightsTour extends JFrame
                 createBoardPanel();
                 
                 /* run the tour in a separate thread */
-                m_startButton.setEnabled(false);
+                m_startButton.setVisible(false);
+                m_cancelButton.setVisible(true);
 
-                new Thread(new TourThread(startx, starty)).start();
+                m_tourThread = new Thread(new TourThread(startx, starty));
+                m_tourThread.start();
+            }
+            else if (e.getSource() == m_cancelButton)
+            {
+                if (m_tourThread != null)
+                {
+                    m_tourThread.stop();
+                    m_tourThread = null;
+                    m_startButton.setVisible(true);
+                    m_cancelButton.setVisible(false);
+                    m_statusLabel.setText("Cancelled.");
+                }
             }
         }
     }
@@ -173,7 +191,8 @@ public class KnightsTour extends JFrame
                     {
                         createBoardPanel();
                         m_statusLabel.setText("Finished.");
-                        m_startButton.setEnabled(true);
+                        m_startButton.setVisible(true);
+                        m_cancelButton.setVisible(false);
                     }
                 });
             }
@@ -184,10 +203,12 @@ public class KnightsTour extends JFrame
                     {
                         createBoardPanel();
                         m_statusLabel.setText("Solution not found!");
-                        m_startButton.setEnabled(true);
+                        m_startButton.setVisible(true);
+                        m_cancelButton.setVisible(false);
                     }
                 });
             }
+            m_tourThread = null;
         }
     }