Qt Open Source License :: Mixing GPL and closed-source license

[wysota]

Thanks for the infos. Well, probably it's okay to link to the closed-source libs in my case because every modern Windows ships with some sort of Windows Media Player, so the libs kind of ARE a de facto OS component.

There are not Open Source as their sources are not available, so that already makes them GPL-incompatible, no matter if they are shipped with the system or not. Windows Media Player component is not a part of the system. And even if it was, it doesn't change anything, it's still GPL incompatible.

As for the media player itself, you could use it in a GPL'd app as an activeX component, provided that you make it possible to use some other component in its place.

[Brandybuck]

And even if it was, it doesn't change anything...

Yes it does! Otherwise you couldn't use win32 or any other standard Windows library. The GPL makes an explicit exception for system components. Specifically, the exception clause covers anything "distributed with" the system components. In other words, if it's on the Windows or Visual Studio CDs, you're probably covered.