Since Gnome 2.10, the Gnome desktop adopt it's menu specification(http://standards.freedesktop.org/menu-spec/latest/).Menus used to be defined as a filesystem hierarchy.In this spec, application's menu isn't organized at root of "applications" item, which need be categorized to a type first, such as Office,Development,Games and etc.
For example, if we deploy a application to menu by such a jnlp file:
<information>
<title>MyApp</title>
<shortcut>
            <menu submenu="MyTools"/>
...
It used to locate at "Launch/Applications/MyTools/MyApp", but now you need to specify a category first. If you don't declare a category in .desktop, the menu will located at "Launch/Other/..." as my test in JDS4(Gnome2.14).
For a user who want to create menu in Gnome, it should have a method to declare its category.Or we can just put all javaws's app under a certain category, but it don't fit for the purpose of category.