public class PleaseWaitPopup extends PopupScreen {
    private PleaseWaitPopup(String msg) {
        super(new VerticalFieldManager());
        add(new LabelField(msg));
    }

    /**
     * This method shows the user a 'please wait' dialog while waiting for a monitor to be unlocked.
     * Execution of the current thread is blocked until the monitor is unlocked.
     * @param msg Message to be shown to the user
     * @param monitor
     */
    public static void waitForUnlock(String msg, final Object monitor) {
        final PleaseWaitPopup popup = new PleaseWaitPopup(msg);
        final UiApplication app = UiApplication.getUiApplication();

        Thread t = new Thread() {
            public void run() {
                app.invokeLater(new Runnable() {
                    public void run() {
                        app.pushModalScreen(popup);
                    }
                });

                synchronized(monitor) {}

                app.invokeLater(new Runnable() {
                    public void run() {
                        popup.close();
                    }
                });
            }
        };

        t.start();
    }

}