How to generate menu buttons dynamically?

Hello,

I tried to create a menu button depending on what item was chosen from
another menu button... and now I'm stuck. Therefore it would be really
great if someone could answer my questions:

- How can I get the ID of the menu button that triggered the
(onclick)-event? (I want to make it the parent.)
- Where to find more detailed information about the three parameters
of the fn-callback, defined in the MenuItem?
- Is there a way to hand over some kind of parent-button-depending
container to the button constructor?

I searched through the examples and the documentation several times
and somehow always managed to overlook the necessary information.

Since I am still unexperienced with YUI and JS, I hope that someone
can help me.

Greetings,
Hannes