[pygtk] HandleBox like a post-it

[Gendag]

Hi,
this is my first message on that mailing list. :-)

I'm searching a widget to create a sort of "post-it" inside a TextView, 
I'd like to have some floating windows where the user can put some text 
to comment part of the text inside the TextView, like when you comment 
part of a lyrics or a book paragraph. I'd like to realize these comments 
as floating windows inside the main TextView but I don't find the right 
widget. I need something similar to an HandleBox, but the movement of 
the floating window must be limited to the container widget (the main 
TextView, in my case). Does this widget exist?

thank you,

Andrea Forni