The menu /submenu functionality is in my new version of Kymaera now. It allows you to use lists that have "sub-lists" as well. I have changed the functionality of the "Select" key to support this. Previously, "Select" would launch the highlighted game, now, "Select" will either
a) launch a game (if the current item in the list is a game)
b) enter into a new list (if the current list item is a sub-list)
I have also added a "Back" button, which will take you out of the sub list back to the previous list.
You can have as many sub-lists and levels of sub-lists as you like, and you can mix sub-lists in a list with games.
Now that I have that all working, I'm adding in the capabilities to the skins to have a Emulator Select screen, so you can select the Emulator, select a list , sublist, and then game.
I've checked out the source code for Lemon Launcher and Game launcher, They are both very well written, and gave me some insight.
Look for a release in the next few days (a week tops).
-PMF