Changing code of an LGPL project and licenses on installers

Question

I have a project I am working on, which links to:

• Qt
• Qt Solutions' QtSingleApplication
• Botan

I have a license dialog in my application, which shows the licenses for the application itself and everything it links to. I have a couple questions regarding the distribution process.

• Do I have to present the licenses in the installation program before the program can be installed and/or as standalone files? Or is it OK to simply include them in a dialog in the main executable?

• I am not using the version of Botan from the official website, but rather the version from the Qt Creator 2.0 sources, which includes a couple of .pro files making it much easier to incorporate it with Qt projects. Botan itself is licensed under a BSD-style license, but Qt Creator 2.0 is licensed under GPL. I'd also like to add around two lines of code to the .pro file to better integrate Botan with my build process. Do I have to release those changes (all it is is changing the output directory in the .pro file, no changes to the C++ code of Botan)? Because Qt Creator is GPL, does this override the Botan license and force me to license my application under GPL? Or will I have to "borrow ideas" from the .pro files found with Qt Creator's Botan and make my own, thus falling under the BSD license?

EDIT: Apparently Qt Creator is licensed under the LGPL (source: the source code).

Answer 1

Whether or not you have to display the licenses at install time depends on the details of the individual licenses. In general, it is usually sufficient to mention in your documentation (and often in the app's "about" box) that the code is licensed under the LGPL and provide the license text in a separate text file. As a courtesy, most GPL-ed apps display the license in place of the traditional EULA in an installer. If your app is not GPL-ed and is simply linking to unmodified, GPL-ed components, then you may not need to make their license as prominent in the installer (a note below your app's EULA that says "contains components licensed under the LGPL" with a link to the LGPL text may suffice). You must still clearly state that you are using LGPL-ed components in your documentation, however, and include the license text or a link to it.

To be safe, it's probably best to make your own modifications to the .pro files. That way, you can make sure that the BSD license remains in effect. You may want to read Qt Creator's documentation carefully, as it might clarify the license in effect on these modified files.