QT sous double licence. QT/X11 est dispo sous GPL.
http://www.wxwindows.org/(...)
"The wxWindows 2 licence is essentially the L-GPL (Library General Public Licence), with an exception stating that derived works in binary form may be distributed on the user's own terms. This is a solution that satisfies those who wish to produce GPL'ed software using wxWindows, and also those producing proprietary software."
[^] # Re: Python in a Nutshell
Posté par Benoît Sibaud (site web personnel) . En réponse à la dépêche Python in a Nutshell. Évalué à 1.
http://www.wxwindows.org/(...)
"The wxWindows 2 licence is essentially the L-GPL (Library General Public Licence), with an exception stating that derived works in binary form may be distributed on the user's own terms. This is a solution that satisfies those who wish to produce GPL'ed software using wxWindows, and also those producing proprietary software."