My python programs need a GUI, wxPython or PyQt4?

Chris Mellon arkanes at
Wed Jan 24 10:32:40 EST 2007

On 1/24/07, Giovanni Bajo <noway at> wrote:
> On 24/01/2007 1.45, Joshua J. Kugler wrote:
> >> I've downloaded both the wxPython and the PyQt4 package, and by the
> >> first impression I must say that the PyQt4 system had a very
> >> compelling presentation. From what I can understand from the feedback
> >> I've gotten so far is that the wxPython is a better choice when it
> >> comes to compability (with linux), and it's free even if I want to
> >> create applications and sell them.
> >> So, from what I understand I will have to go with PyQt4 since (from
> >> my understanding):
> >> 1. I will not sell the applications I'm working with since they will
> >> only be used by the internal QA at a computer game company.
> >
> > Even that is getting on shaky ground, at least according to Troll Tech.
> > See:  So, write it
> > for internal use, and put up for distribution on your personal web site
> > (pending company approval, of course).
> That page is legal babble, trying to trick you into buying (or making your
> boss buy) a commercial license. The Qt Open Source edition *IS* GPL and thus
> it falls under all the normal GPL clauses and uses, irrespective of what
> Trolltech may or may not think.
> For instance, see this FAQ:
> which makes pretty clear that a "company"/"organization" is basically the same
> of an "individual". "Releasing a software within a company for internal usage"
> is by no means the same of "releasing it to the public". Basically, for what
> the GPL is concerned, it is *not* a "release" or a "distribution" at all.

I should point out that the FSFs position in this regard is not
supported by copyright law and that the fact that Trolltech takes a
different position is something that you should consider strongly. If
the FSFs position were true, there would be no need for per-seat
licensing of commercial software (because internal distribution
wouldn't be). US copyright law does not draw a distinction between
"internal distribution" and any other kind, and I'm not aware of any
case law that does so either. This distinction is also not codified in
the GPL itself anywhere, so it's not a necessary condition of the
license - it is an interpretation by the FSF and that is all.

> Thus, it is well possible to write internal GPL software, using the Qt Open
> Source library, and to release/distribute/use it *ONLY* internally. Also, it
> should be made clear that a company can of course relicense its own
> proprietary libraries as GPL for internal usage only, so that they can be
> linked to other GPL libraries "legally". For instance, in the case of Daniel
> and his game company, they can link their proprietary game code to PyQt4 (Open
> source edition) to produce an internal tool, like a level editor, which would
> then fall under the GPL. If and only if they were to release that tool to the
> public (either for free or for sale), they would have to either go GPL and
> release full source code (include the parts of their game code linked to it),
> or buy a Qt commercial license.
> [[ Another page of similar babble is the one where they try to convince you
> that you cannot use the Qt Open Source edition to develop a software, and then
> buy the commercial edition only the day before you want to release it as non
> open-source. I can't even understand how they can even try to support such a
> nonsense position. You're free to develop your software for years as GPL
> without distributing it, and then relicense your own code whenever you want.
> They're obviously just trying to scare people. ]]
> --

Trolltech can do this because they won't sell you a commercial license
if they think you've been using the GPL version to develop. It's a
practical limitation, not a legal one.

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