From: John Gabriele <jmg3000@...>
Date: 2006-09-28T05:00:14+09:00
Subject: Re: Ruby with Qt or GTK ?

On 9/27/06, Tom Pollard <tomp@earthlink.net> wrote:
>
> Someone using your software under the GPL does not have the right to
> use it for any purpose.

then:
> [snip]  The GPL just restricts what someone using your software can
> legally do with it.  It's still your software.

That sounds incorrect. You, the user, can use GPL'd software for
whatever you like. For example, you may build proprietary software
with gcc if you like.

The GPL has to do with distribution -- it talks about the rules you
need to follow if you want to *distribute* GPL'd software. It has
nothing to do with what you *use* it for.

You can download some piece of GPL'd software, modify it to your
heart's content, and then keep the code secret if you like. If you're
a company, you can use your modified copy in-house and never release
your changes to the public. However, if you *do* release your changes
(say, by distributing them to one of your customers), then the GPL
kicks-in and says you must supply the source also.

If you use Qt to build some cool GUI program, your program is not
automatically GPL'd, but it is, however "a work based on" Qt; aka, a
"derivative work" (since your program links to Qt). Now, if you then
begin to sell or otherwise distribute or publish your program,
TrollTech (the copyright holder of Qt) says (via the GPL) that you
must at that point provide it under the same terms as Qt itself (the
GPL).

As Tom points out, the copyright holder may, at any time, re-license
their code as they see fit. If version 1.2.3 is GPL, they can
re-release that version (or release later versions) under some other
license But if a user downloaded v1.2.3 when it was GPL'd, then I
think that particular snapshot is forevermore GPL'd.

Anyhow, I believe this is the main reason the bigger players prefer
GTK+ (which is LGPL'd) to Qt (which some argue is superior to GTK+).

As a general point of interest here, note that Ruby itself is
currently dual-licensed (GPL (no version given) and Matz's own terms
(very similar to the artistic license)).

---John