How can I get the size of a container ???

[Sergio Trinidad <strinidadr gmail com>]

Hello,

I have a label inside a vbox, and i need to know the height of the label 
or the vbox to change the size of the text to fill all available area when
the size of the label changes.

I do this with on_configure_event but it seems to only work with a window
and not with a vbox. Any solution ?

Thanks in advance