Java Code:
import org.eclipse.swt.SWT;
import org.eclipse.swt.custom.SashForm;
import org.eclipse.swt.events.ControlEvent;
import org.eclipse.swt.events.ControlListener;
import org.eclipse.swt.events.MouseEvent;
import org.eclipse.swt.events.MouseListener;
import org.eclipse.swt.layout.FillLayout;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Label;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.swt.widgets.Text;

public class SashFormExample {
  Display display = new Display();
  Shell shell = new Shell(display);
  SashForm sashForm;
  SashForm sashForm2;

  public SashFormExample() {
    shell.setLayout(new FillLayout());
    sashForm = new SashForm(shell, SWT.HORIZONTAL);
    Text text1 = new Text(sashForm, SWT.CENTER);
    text1.setText("Text in pane #1");
    Text text2 = new Text(sashForm, SWT.CENTER);
    text2.setText("Text in pane #2");
    sashForm2 = new SashForm(sashForm, SWT.VERTICAL);
    final Label labelA = new Label(sashForm2, SWT.BORDER | SWT.CENTER);
    labelA.setText("Label in pane A");
    final Label labelB = new Label(sashForm2, SWT.BORDER |SWT.CENTER);
    labelB.setText("Label in pane B");
    text1.addControlListener(new ControlListener() {
      public void controlMoved(ControlEvent e) {
      }

      public void controlResized(ControlEvent e) {
        System.out.println("Resized");
      }
    });
    sashForm.setWeights(new int[]{1, 2, 3});
    labelA.addMouseListener(new MouseListener() {
      public void mouseDoubleClick(MouseEvent e) {
        if(sashForm2.getMaximizedControl() == labelA)
          sashForm2.setMaximizedControl(null);
        else
          sashForm2.setMaximizedControl(labelA);
      }

      public void mouseDown(MouseEvent e) {
      }

      public void mouseUp(MouseEvent e) {
      }
    });
    shell.setSize(450, 200);
    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 SashFormExample();
  }
}