[TYPO3] Create and render a menu in extension

[Gary Wong]

Hello,

I am building an extension FE plugin where, in the extension code, I 
would like to define and create a TMENU (or GMENU in the future).  I'd 
like the extension to call the appropriate methods to render it, then 
have the rendered HTML content in a var.

Can anyone give me some pointers as to do this or point me to an example 
where this is done in the extension plugin code?

Thank you very much,
Gary