Using code from Qt's demos in KDE applications

Ingo Klöcker kloecker at
Mon Aug 3 22:18:11 BST 2009

On Monday 03 August 2009, Olivier Goffart wrote:
> Le Monday 03 August 2009, Stefan Majewsky a écrit :
> > Hi,
> >
> > my GSoC student Zeng Huan is currently working on a heightmap
> > editor for Kolf. For a brush tool, he currently uses some code from
> > the Qt demo on gradients.
> >
> > What is the preferred way to correctly attribute the origin of the
> > source code? We have already left the Qt license header in the
> > source file, but should we make some extra attribution in the about
> > dialog or such?
> It is not required to (although you can) add reference in the UI to
> code borrowed from Qt or any GPL project.

True, but things are different for code released under the LGPL.

> You just need to respect the (L)GPL  which I guess you do as your
> project is GPLv2 itself from what I seen
> So as soon as you keep the copyright notice with the file, that's
> fine.

LGPL 2.1 states in paragraph 6:
"If the work during execution displays copyright notices, you must 
include the copyright notice for the Library among them, as well as a 
reference directing the user to the copy of this License."

IANAL, but AFAIU this means, that if the About dialog does display a 
copyright notice then one has to include the copyright notice of those 
portions of the Library that the work contains.

The GPL does not have such a requirement and since Kolf is GPL the Qt 
code can be used under the GPL without the need to include any 
copyright notices in the About dialog.

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