public class ShellTest {
public static void main(String[] args) {
    final Display display = Display.getDefault();

    final Shell shell = new Shell(display, SWT.SHELL_TRIM);
    shell.setLayout(new GridLayout());

    shell.addListener(SWT.ZoomChanged, new Listener() {
        @Override
        public void handleEvent(Event event) {
            System.out.println("ZoomChanged: " + event);
        }
    });

    Button btn = new Button(shell, SWT.PUSH);
    btn.setText("Test");

    shell.open();
    shell.layout();
    while(!shell.isDisposed()) {
        if(!display.readAndDispatch()) {
            display.sleep();
        }
    }
}
}