Panel and subpanels in Nifty-Gui

Hi,



I am trying to create a main menu panel and sub panels. Sub panels would become visible when a mouse is on a specific icon on the main menu (menu would operate much like windows start menu).



I have managed to use nifty-gui on JME2 and create the main menu. I haven't still figured out how could I create sub menus (or turn then visible) when mouse is on a specific icon on the main menu.



I would like to ask, how do I create such sub menus? What kind of XML -code and java code I need to write?



Thanks

I think this could be the same topic: http://sourceforge.net/projects/nifty-gui/forums/forum/807893/topic/3747550