Fixed warning

src/gui/MainWindow.java

@@ -4,6 +4,8 @@ import javax.swing.JFrame;
 
 public class MainWindow extends JFrame{
 
+	private static final long serialVersionUID = 13L;
+
 	public MainWindow(){
 		JFrame fenetre = new JFrame();
 		fenetre.setTitle("Client");

src/gui/Parameters.java

@@ -11,6 +11,7 @@ import java.awt.GridLayout;
 
 public class Parameters extends JPanel{
 
+	private static final long serialVersionUID = 13L;
 	private JLabel label1, label2, label3, label4, label5;
 	private JTextField field1, field2, field3, field4;
 	private JButton connectButton;

src/gui/downloadSelection.java

@@ -12,12 +12,13 @@ import java.awt.GridLayout;
 
 public class downloadSelection extends JPanel {
 
-  private String[] listFilesToDownload;
-  private JList<String> list1;
-  private JLabel label1;
-  private JButton downloadButton;
+	private static final long serialVersionUID = 13L;
+	private String[] listFilesToDownload;
+	private JList<String> list1;
+	private JLabel label1;
+	private JButton downloadButton;
 
-  public downloadSelection(String[] listFilesToDownload){
+	public downloadSelection(String[] listFilesToDownload){
 		JPanel p1 = new JPanel();
 		JPanel p3 = new JPanel();
 		FlowLayout layout = new FlowLayout();
@@ -35,6 +36,6 @@ public class downloadSelection extends JPanel {
 		this.add(p1);
 		this.add(p3);
 		setVisible(true);
-  }
+	}
 
 }