With the following code I get a label. The text inside the label should be 
justified across the label (since I asked JUSTIFY_FILL). But It does not work 
(with me, at least :-). JUSTIFY_LEFT, _RIGHT and _CENTER work, but not _FILL
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import gtk 

fenetre = gtk.Window(gtk.WINDOW_TOPLEVEL) 
label = gtk.Label("blabla bla bla blabla bla bla bla-blabla, blabla blabla. 
Blablabla bla blabla bla blabla blabla blablabla bla bla. Blabla bla bla 
blablablabla bla bla bla blabla. Blabla blabla blablabla. Bla blabla bla bla, 
bla bla bla.\nBla blabla bla blablabla.\nBlabla bla blabla bla, blabla, blabla 
blablabla. Bla bla blabla bla bla bla, blablablablabla.") 

label.set_line_wrap(gtk.TRUE) 
label.set_justify(gtk.JUSTIFY_FILL) 

fenetre.add(label) 
fenetre.show_all() 

gtk.main()
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In the GTK+ tutorial, the screenshot at the "Labels" section shows a non-
justified (non filled) label too (but it SHOULD normally be, because of 
JUSTIFY_FILL)