diff --git a/src/dev/kske/chess/ui/AIConfigDialog.java b/src/dev/kske/chess/ui/AIConfigDialog.java
deleted file mode 100644
index 54ef3d3..0000000
--- a/src/dev/kske/chess/ui/AIConfigDialog.java
+++ /dev/null
@@ -1,81 +0,0 @@
-package dev.kske.chess.ui;
-
-import java.awt.Dimension;
-
-import javax.swing.*;
-
-/**
- * Project: <strong>Chess</strong><br>
- * File: <strong>AIConfigDialog.java</strong><br>
- * Created: <strong>16.07.2019</strong><br>
- *
- * @since Chess v0.1-alpha
- * @author Kai S. K. Engelbart
- */
-@Deprecated
-@SuppressWarnings("javadoc")
-public class AIConfigDialog extends JDialog {
-
-	private static final long serialVersionUID = -8047984368152479992L;
-
-	private int		maxDepth;
-	private int		alphaBetaThreshold;
-	private boolean	startGame	= false;
-
-	public AIConfigDialog() {
-		setSize(new Dimension(337, 212));
-		setModal(true);
-		setDefaultCloseOperation(WindowConstants.DISPOSE_ON_CLOSE);
-		setTitle("AI Configuration");
-		getContentPane().setLayout(null);
-
-		JSpinner spAlphaBetaThreshold = new JSpinner();
-		spAlphaBetaThreshold.setBounds(222, 68, 95, 28);
-		getContentPane().add(spAlphaBetaThreshold);
-		spAlphaBetaThreshold.setModel(new SpinnerNumberModel(-10, -100, 100, 5));
-
-		JSpinner spMaxDepth = new JSpinner();
-		spMaxDepth.setBounds(222, 6, 95, 28);
-		getContentPane().add(spMaxDepth);
-		spMaxDepth.setModel(new SpinnerNumberModel(4, 1, 10, 1));
-
-		JLabel lblAlphabetaThreshold = new JLabel("Alpha-Beta Threshold:");
-		lblAlphabetaThreshold.setBounds(16, 68, 194, 28);
-		getContentPane().add(lblAlphabetaThreshold);
-
-		JButton btnOk = new JButton("OK");
-		btnOk.setBounds(16, 137, 84, 28);
-		getContentPane().add(btnOk);
-		btnOk.addActionListener((evt) -> {
-			maxDepth			= ((Integer) spMaxDepth.getValue());
-			alphaBetaThreshold	= ((Integer) spAlphaBetaThreshold.getValue());
-			startGame			= true;
-			dispose();
-		});
-		btnOk.setToolTipText("Start the game");
-
-		JButton btnCancel = new JButton("Cancel");
-		btnCancel.setBounds(222, 137, 95, 28);
-		getContentPane().add(btnCancel);
-		btnCancel.addActionListener((evt) -> dispose());
-		btnCancel.setToolTipText("Cancel the game start");
-
-		JLabel lblMaximalRecursionDepth = new JLabel("Maximal Recursion Depth:");
-		lblMaximalRecursionDepth.setBounds(16, 12, 194, 16);
-		getContentPane().add(lblMaximalRecursionDepth);
-
-		setLocationRelativeTo(null);
-	}
-
-	public int getMaxDepth() { return maxDepth; }
-
-	public void setMaxDepth(int maxDepth) { this.maxDepth = maxDepth; }
-
-	public int getAlphaBetaThreshold() { return alphaBetaThreshold; }
-
-	public void setAlphaBetaThreshold(int alphaBetaThreshold) { this.alphaBetaThreshold = alphaBetaThreshold; }
-
-	public boolean isStartGame() { return startGame; }
-
-	public void setStartGame(boolean startGame) { this.startGame = startGame; }
-}
diff --git a/src/dev/kske/chess/ui/GamePane.java b/src/dev/kske/chess/ui/GamePane.java
index ef88934..4df7095 100644
--- a/src/dev/kske/chess/ui/GamePane.java
+++ b/src/dev/kske/chess/ui/GamePane.java
@@ -177,7 +177,7 @@ public class GamePane extends JComponent {
 				if (game.getBoard().getLog() == null) return;
 
 				DefaultListModel<MoveNode> model = new DefaultListModel<>();
-				game.getBoard().getLog().forEach(node -> model.addElement(node));
+				game.getBoard().getLog().forEach(model::addElement);
 				pgnList.setModel(model);
 			}
 
diff --git a/src/dev/kske/chess/ui/MainWindow.java b/src/dev/kske/chess/ui/MainWindow.java
index 86ae49f..351a67d 100644
--- a/src/dev/kske/chess/ui/MainWindow.java
+++ b/src/dev/kske/chess/ui/MainWindow.java
@@ -37,7 +37,7 @@ public class MainWindow extends JFrame {
 	 *
 	 * @param args command line arguments are ignored
 	 */
-	public static void main(String[] args) { SwingUtilities.invokeLater(() -> new MainWindow()); }
+	public static void main(String[] args) { SwingUtilities.invokeLater(MainWindow::new); }
 
 	/**
 	 * Create the application.
@@ -185,7 +185,7 @@ public class MainWindow extends JFrame {
 		} catch (IOException e) {
 			e.printStackTrace();
 			JOptionPane.showMessageDialog(this,
-					"Failed to save the file " + file.getName() + ": " + e.toString(),
+					"Failed to save the file " + file.getName() + ": " + e,
 					"File saving error",
 					JOptionPane.ERROR_MESSAGE);
 		}