The published documentation for the submenu attribute says only:
(from dev guide):
The shortcut element can contain the optional online attribute, and the two optional sub-elements, desktop and menu.
(from jnlp specification):
The optional submenu attribute can be used to indicate an application's preference for where to place the menu item, and can contain any string value.
The actual implementation is that the submenu element must be a string that can be used as a submenu in the native system. To achive multiple nested submenu's, this may require seperate strings for seperate platforms.
On windows, you can specify multiple nested sub-menus by seperating them with a slash ("/") the example given uses "My Test App/MyTest1/Mytest2" . this works as expected on Windows, but not on Solaris Gnome.
We have to find out if the Gnome implementation can be made to install multiple sub-menus using some other format, and if so, document that it may be necessary to uses OS specific information block such as:
<menu submenu="...GNome form ..."/>
<menu submenu="My Test Apps/MyTest1/MyTest2"/>
If it is not possible with the current Gnome implementation, we need to doc that and fix in mustang.
We may need to doc this anyway since characters allowed in path elements may vary from os to os.