Java Code:
import org.eclipse.swt.SWT;
import org.eclipse.swt.events.PaintEvent;
import org.eclipse.swt.events.PaintListener;
import org.eclipse.swt.graphics.Color;
import org.eclipse.swt.graphics.GC;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.layout.FillLayout;
import org.eclipse.swt.widgets.Canvas;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Group;
import org.eclipse.swt.widgets.Shell;

public class Snippet112 {

  public static void main(String[] args) {
    Display display = new Display();
    final Image image = new Image(display, 20, 20);
    Color color = display.getSystemColor(SWT.COLOR_RED);
    GC gc = new GC(image);
    gc.setBackground(color);
    gc.fillRectangle(image.getBounds());
    gc.dispose();
    color.dispose();

    Shell shell = new Shell(display);
    shell.setLayout(new FillLayout());
    Group group = new Group(shell, SWT.NONE);
    group.setLayout(new FillLayout());
    group.setText("a square");
    Canvas canvas = new Canvas(group, SWT.NONE);
    canvas.addPaintListener(new PaintListener() {
      public void paintControl(PaintEvent e) {
        e.gc.drawImage(image, 0, 0);
      }
    });

    shell.pack();
    shell.open();
    while (!shell.isDisposed()) {
      if (!display.readAndDispatch())
        display.sleep();
    }
    image.dispose();
    display.dispose();
  }
}