Re: [gtk-list] Re: Gtk+ Commercial Applications (Licencing Issues)

GTK+ is under the LGPL, which can be found at:
The GPL can be found at:

I am not a lawyer. The rest of letter contains what I believe to be
  clarifications the LGPL, and the GPL. If you really care, go read the
  original. If you believe what I say here, and suffer for it, I refuse to
  accept any blame for your suffering.
I believe the original question was more or less as follows:

If I use GTK+ in a propriety application, can I distribute that
  application under a traditional restrictive proprietary software
  Yes you can. You may distribute it under any license you want. The    
    LGPL is basically the GPL with a clause that allows an application
    to use LGPL'd software as library, and still be distributed under
    the author's license of choice ... so long as there is no *other*
    reason why the GPL might cover that application.

  HOWEVER, if you modify GTK+ itself (as opposed to just using it as a
    library), you must ensure that whoever gets binaries of the modified
    GTK+ can also get the source that was compiled into those binaries.
      Example (1): Suppose I write Gargle, a gargling application,
        which uses GTK+, and I want to distribute Gargle under a
        binary-only license that does not allow anyone (except me) to
        distribute copies of Gargle. The LGPL allows this, even if the
        binaries of Gargle that I distribute are statically linked to

      Example (2): Suppose I modify GTK+ itself (as opposed to just
        using it as a library), and call the modified version
        Super-Duper-GTK+. Suppose I want distribute this modified
        version of GTK under a binary-only license that does not allow
        anyone (except me) to distribute copies of
        Super-Duper-GTK+. This would be illegal. The LGPL does *NOT*
        allow this. (To be compliant with the LGPL, I would have to
        distribute source with binaries, and allow anyone who had
        copies to make and distribute copies.)

If you feel you need more clarification, go read the original
  license(s) at the URLs given above, or read on.

Since the LGPL is based on the GPL, I will explain the GPL
  first. Those of you who are interested in the LGPL, read my
  explanation of the GPL first, then go back and re-read my answer to
  the original question, above. I believe that clarifies the
  difference between the LGPL and GPL as much as I am able to.

The GPL can be summed up more or less as follows:
  (0) Sharing. The GPL is designed to ensure that if someone has a copy of
      a piece of GPL'd software, they can always share it with anyone
      they want.
  (1) Whoever gets the binaries, must also get (or be able to get) the
      source code that produced the binaries.
  (2) Whoever has binaries and source can redistribute them to whoever
      they want... so long as they provide both binaries and source.
  (3) If you modify or add to a project which is under the GPL, your
      additions/modifications must be distributed with the whole as if it
      where under the GPL... or not distributed at all. If you add
      some GPL'd code to a pre-existing project which was *not* under
      the GPL, the same restrictions apply: the whole project,
      including the original non-GPL'd code, must be distributed under
      the GPL. (This is the part that some people label as 'viral'.)
  (4) The GPL does not *require* anyone to redistribute GPL'd software ...
      it just requires that source must come with binaries.
      You are specifically allowed to take GPL software, modify it, and 
      keep your modified copies on a hard drive in a safe with no NIC, and
      give neither binaries nor source to anyone.
      You are allowed to give binaries and source to only your best
      friend, (for example) and not give it to anyone else.
      HOWEVER, if said best friend decides to post both binaries and      
      source on his web page for the whole world to download, you can't   
      complain, even if you made him sign in blood a contract that said he
      would do no such thing. (This is where Corel messed up; they tried
      to make their beta-testers agree not to redistribute their linux
   (5) The GPL says *nothing* about how much you can or can't charge for  
       software; company Foo is allowed to sell its FooLinux distro for   
       $3000 per copy, if they want to. However, anyone who gets a copy is
       allowed to give it away to the world.
   (6) There are 3.141592654 important legal points I have left out. Kudos
       to anyone who can remember them.
   (7) The above is useful for entertainment purposes only. If you really
       need to know:
       (1) Get the GPL from, and read
       (2) Go find a trustworthy lawyer. Make the lawyer read it.
       (3) Make the lawyer explain it to you.

Now that I have discussed the GPL far longer than I intended (I should
  have just posted the whole license), I will terminate this letter.


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