[TxMt] invoking a snippet from a snippet

[Michael Sheets]

> I wanted to do exactly the same thing, but as far as I can tell you
> can't.  I'd also really like for the snippets to be properly nested,
> such that when you finish the second one, it carries on with the rest
> of the first.

Right this is not possible right now. You can only envoke another  
snippet after you reach $0 (which is reached after you tab past the  
last placeholder), or you break out of the snippet mode by moving  
outside the snippet, etc.