Java Code:
import org.eclipse.swt.SWT;
import org.eclipse.swt.layout.FillLayout;
import org.eclipse.swt.widgets.Button;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;

public class FillLayoutSample {
  Display display = new Display();
  Shell shell = new Shell(display);

  public FillLayoutSample() {
    FillLayout fillLayout = new FillLayout(SWT.VERTICAL);
    fillLayout.marginHeight = 5;
    fillLayout.marginWidth = 5;
    fillLayout.spacing = 1;
    shell.setLayout(fillLayout);
    Button button1 = new Button(shell, SWT.PUSH);
    button1.setText("button1");
    Button button2 = new Button(shell, SWT.PUSH);
    button2.setText("button number 2");  
    Button button3 = new Button(shell, SWT.PUSH);
    button3.setText("3");    

    shell.pack();
    shell.open();
    //textUser.forceFocus();

    // Set up the event loop.
    while (!shell.isDisposed()) {
      if (!display.readAndDispatch()) {
        // If no more entries in event queue
        display.sleep();
      }
    }

    display.dispose();
  }

  private void init() {

  }

  public static void main(String[] args) {
    new FillLayoutSample();
  }
}