GTK+ Forums

metalzelot · Joined: 14 Mar 2007 Posts: 4

I've been asked to develop an application for a small firm which supports e-books in a special way. It will be a commercial application so you have to pay for using it. My question is if it is possible to use GTK as a development kit, am I allowed to package GTK into this application?
The program will mainly run at windows.

Actually I'm a linux and free software supporter so I'd like to use GTK now too. My other possibility would be QT.

Micah Carrick · Posted: Wed Mar 14, 2007 7:41 pm Post subject:

Not my area of expertise-- you'd want to be certain-- but I think so.

metalzelot · Joined: 14 Mar 2007 Posts: 4

Isnt there a difference between proprietary and commercial software?

proprietary: freeware but closed source
commercial: software you have to pay for

And this still doesnt explain if I'm allowed to bind my program with GTK for easier installation on windows.

Micah Carrick · Posted: Wed Mar 14, 2007 8:24 pm Post subject:

openldev · Posted: Wed Mar 14, 2007 8:40 pm Post subject:

You can build any application against GTK+ since it is licensed under the LGPL, even if it is closed source. The only thing is that, if you make any changes to any open source libraries, you must provide those changes as open source.

As for Qt, it is licensed under the GPL, so you cannot do this unless you buy a commercial license. In fact, you cannot sell software linked against Qt unless you pay Trolltech. Check out these links for more Qt info:

http://www.trolltech.com/products/qt/licenses/pricing
http://www.trolltech.com/products/qt/licenses/licensing/licensingoverview

I would recommend going with GTK+ for your project. However, you should really keep as much of the application open as possible. This is not required by the license, but it is good nature to try and open up as much as possible when you are linking against something that people provided to you for free.

metalzelot · Joined: 14 Mar 2007 Posts: 4

If it would be up to me it would be open source anyway :)

But as I said its for another business and they want to sell this software. I'm aware that I have to pay licenses for Qt, but that wouldnt be the problem because the program will be sell some tenthousand times.

So it means if I dont change the source of GTK+ (what Im not intended to do) I dont have to include sources to the install.exe etc... ?

openldev · Posted: Wed Mar 14, 2007 10:52 pm Post subject:

Exactly. As long as someone can run your application with the standard libraries, you are in the clear.

metalzelot · Joined: 14 Mar 2007 Posts: 4

Okay, great :)

thanks for your information and for your help

caracal · Posted: Fri Jun 29, 2007 2:50 am Post subject:

caracal · Posted: Thu Sep 13, 2007 5:08 pm Post subject:

Ok here is how it works if your building a commercial application and you use a GPL library like
poppler or libpurple then your application has to also be licenses GPL even if your just linking to they library.

But if your using a library that is LGPL like Gtk and your just linking to they library then your fine to close source your application as the LGPL lets you do this but you cant bundle they library with your package as your program would then have to be licenses under the LGPL or greater and be open source.

But if your using a library that uses a zlib, MIT/X11, BSD like licenses like libxml2 then you can package the library up with your application and close source it as these licenses allow you to do that.

Now if you using a library that is dual licenses like Gtk+ Webcore "LGPL & BSD" you can include they BSD parts and Close Source your application but they minute you touch they LGPL licenses code then your application has to conform to they LGPL licenses in this situation if your not going to rewrite all of they LGPL code then its best to just link to Gtk+ Webcore.

Reference:
1. If you use GPL code then your program has to be licenses GPL no matter what.
2. If you use LGPL code
2.A. Include they LGPL lib and release your software under a GPL compatible licenses.
2.B Link to the LGPL lib and release your code under any licenses you want.
3. If you use a zlib, MIT/X11, BSD type licenses your free to do as you wish.

When we say commercial application we mean closed source you can always sell any GPL compatible software for profit.

Now what would happen if you violated an open source licenses?
Well first off you would be taken to court if you refused to open source your software & release code then you would be sued by every person who ever
contributed code to that project that you violated.
Then you would just have to open source your code anyway.

So as a reminder to all who build closed source applications be careful about how you use GPL or LGPL code.

And to answer this question.
Am I allowed to package GTK into this application?

Your answer is sure if you want to release your application under a LGPL or greater licenses and provide anyone who receives your software with the source code.

ZuLuuuuuu · Familiar Face Joined: 20 Dec 2007 Posts: 6

Also the official tutorial mades it very clear:

caracal · Posted: Mon Jan 07, 2008 7:53 am Post subject:

http://answers.google.com/answers/threadview?id=439136