diff -r e70a0e3555fb -r 576e7a2861ae src/main/java/de/uapcore/sudoku/Sudoku.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/main/java/de/uapcore/sudoku/Sudoku.java	Sat Jul 25 14:01:28 2020 +0200
@@ -0,0 +1,69 @@
+/*
+ * 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 javax.swing.*;
+import java.awt.*;
+
+/**
+ *
+ * @author mike
+ */
+public final class Sudoku extends JFrame {
+    
+    public Sudoku() {
+        super("Sudoku");
+        
+        Field f = new Field();
+        ActionHandler h = new ActionHandler(f);
+        setJMenuBar(new MainMenu(h).getMenuBar());
+        
+        Container content = getContentPane();
+        
+        content.setLayout(new GridBagLayout());
+        GridBagConstraints c = new GridBagConstraints();
+        c.insets = new Insets(20, 20, 20, 20);
+        c.fill = GridBagConstraints.HORIZONTAL;
+        
+        c.gridx = 0; c.gridy = 0;
+        content.add(f, c);
+        c.gridy++;
+        content.add(new ButtonPanel(h), c);
+        
+        pack();
+        content.setBackground(Color.WHITE);
+        setLocationByPlatform(true);
+        setDefaultCloseOperation(EXIT_ON_CLOSE);
+    }
+
+    /**
+     * @param args the command line arguments
+     */
+    public static void main(String[] args) {
+        new Sudoku().setVisible(true);
+    }
+}