added a comment

src/fi/utu/dtek1066/MapDialog.java

@@ -158,6 +158,7 @@ public class MapDialog extends JFrame {
     this.zoomInB.addActionListener(bl);
     this.zoomOutB.addActionListener(bl);
 
+    // Timer for delaying image updates when resizing the window
     this.resizeTimer = new Timer(250, new ActionListener() {
       @Override
       public void actionPerformed(ActionEvent evt) {