[pygtk] Left justify content of Vbox.

[Fabian Sturm]

Ohh yes that's true, a label has already a xalign property builtin. 

:-)

> try: label.set_alignment(0, 0.5)
> 
> http://www.pygtk.org/pygtk2reference/class-gtkmisc.html#method-gtkmisc--set-alignment
>