Tutorial XML- dynamic navigation by senocular

Hallo !

I have a little question on a tutorial from senocular at Kirupa.com.
Anybody watched the source code ?
My question is on the “ActionObject”-Part:
Why do I need action.message and action.newMenu ?
And another question: At the relativ beginning in the Source, there´s the command “curr_item.trackAsMenu = true”. I know the definition, but why and when do I need to tell other parts my events ?

ThanX a lot for helping…

Yours, MrHonse