Hide & show main window

[Daniel Iwan GM]

I would like to hide / show main frame of the application created with
DesktopApplicationContext.main(HelloWTKX.class, args);
Basically it's because I want to keep it in system tray.

window.setVisible(false)

hides only the content of the window while
window.getParent.setVisible(false)
display message

Exception in thread "main" java.lang.UnsupportedOperationException: Can't
change the visibility of the display.
    at org.apache.pivot.wtk.Display.setVisible(Unknown Source)
    at com.daniel.iwan.nmtfeeder.gui.pivot.HelloWTKX.main(HelloWTKX.java:64)

Thanks