Java Code:
import java.util.ResourceBundle;

import org.eclipse.swt.SWT;
import org.eclipse.swt.events.ControlAdapter;
import org.eclipse.swt.events.ControlEvent;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Label;
import org.eclipse.swt.widgets.Shell;

/*
 * This example builds on HelloWorld2 and demonstrates how to resize the 
 * Label when the Shell resizes using a Listener mechanism.
 */
public class HelloWorld3 {

  public static void main(String[] args) {
    Display display = new Display();
    Shell shell = new HelloWorld3().open(display);
    while (!shell.isDisposed()) {
      if (!display.readAndDispatch())
        display.sleep();
    }
    display.dispose();
  }

  public Shell open(Display display) {
    final Shell shell = new Shell(display);
    final Label label = new Label(shell, SWT.CENTER);
    label.setText("Hello_world");
    label.pack();
    shell.addControlListener(new ControlAdapter() {
      public void controlResized(ControlEvent e) {
        label.setBounds(shell.getClientArea());
      }
    });
    shell.pack();
    shell.open();
    return shell;
  }
}