diff -r 5179eff8a9b6 -r ed931970b4ac src/de/uapcore/sudoku/ActionHandler.java
--- a/src/de/uapcore/sudoku/ActionHandler.java	Sat Jan 26 17:42:07 2013 +0100
+++ b/src/de/uapcore/sudoku/ActionHandler.java	Sat Jan 26 18:38:12 2013 +0100
@@ -1,3 +1,29 @@
+/*
+ * Copyright 2013 Mike Becker. All rights reserved.
+ * 
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ * 
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
 package de.uapcore.sudoku;
 
 import java.awt.event.ActionEvent;
@@ -14,6 +40,12 @@
     public static final String CHECK = "check";
     public static final String SOLVE = "solve";
     
+    public static final String NEW = "new";
+    public static final String OPEN = "open";
+    public static final String SAVE_AS = "save as";
+    public static final String QUIT = "quit";
+    public static final String ABOUT = "about";
+    
     private Field field;
     private Solver solver;
     
@@ -22,14 +54,16 @@
         solver = new Solver();
     }
     
-    private void save() {
+    private boolean save() {
         if (solver.check(field)) {
             field.setAllCellsModified(false);
             // TODO: save to file
+            return true;
         } else {
             JOptionPane.showMessageDialog(field,
                     "Das Feld kann mit Fehlern nicht gespeichert werden!",
                     "Sudoku", JOptionPane.ERROR_MESSAGE);
+            return false;
         }
     }
     
@@ -50,15 +84,37 @@
     @Override
     public void actionPerformed(ActionEvent e) {
         switch (e.getActionCommand()) {
-        case "save":
+        case SAVE:
             save();
             break;
-        case "check":
+        case CHECK:
             check();
             break;
-        case "solve":
+        case SOLVE:
             solve();
             break;
+        case QUIT:
+            if (field.isAnyCellModified()) {
+                int result = JOptionPane.showConfirmDialog(field,
+                        "Das Feld ist ungespeichert - jetzt speichern?",
+                        "Sudoku", JOptionPane.YES_NO_CANCEL_OPTION);
+                if (result == JOptionPane.YES_OPTION) {
+                    if (save()) {
+                        System.exit(0);
+                    }
+                } else if (result == JOptionPane.NO_OPTION) {
+                    System.exit(0);
+                }
+            } else {
+                System.exit(0);
+            }
+            break;
+        case ABOUT:
+            JOptionPane.showMessageDialog(field,
+                    "Sudoku - Copyright (c) 2013 Mike Becker\nwww.uap-core.de"+
+                    "\nPublished under the BSD License",
+                    "Sudoku", JOptionPane.INFORMATION_MESSAGE);
+            break;
         default:
             throw new UnsupportedOperationException(
                     "unknown action: "+e.getActionCommand());