[Qt-interest] Help understanding the move to LGPL

[Justin Noel]

IANAL (I Am Not A Lawyer), but here are the generalities:

> Please redirect me if this is off topic.
>
> Given : an application written using the open source distro of Qt 4.5
>
> Question: Do I have to release the source ?   I have seen info that says I do not.
>   

You do not have to distribute the source for you applications given that
your application is compatible for use with LGPL libraries. You have to
make sure that the end user can replace your version of the LGPL library
with their own and your app will still work. Compliance can simply be to
dynamically link against Qt.

You can read the entire LGPL 2.1 licence here:
http://www.gnu.org/licenses/lgpl-2.1.txt Also, ICS has a new whitepaper
detailing the simple steps to making sure your application (or
libraries) are compatible with LGPL libraries. The whitepaper is located
here: http://www.ics.com/files/docs/Qt_LGPL.pdf on http://www.ics.com.
> Question: Am I permitted to charge for it ?  I have seen info that leads me to believe that I am allowed to.
>   

You can charge as much as you like for your application. The LGPL states
that you can have whatever license you want for your application as long
as you make available the version of the LGPL'd libraries to your
customers including any changes you make to the LGPL'd library itself.
If you are using a stock Qt version from Trolltech's website you could
provide something like a mycompany.com/opensource which links to Qt
Software's site and list your opensource page in your application's
documentation.

Good Luck!
--Justin
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