Peony is a file manager application and is a part of UKUI Desktop Environment. It provides a library, which allow who do a secondary development under LGPLv3. This means a developer can develop a file manager application like Peony, and reserve its licenses and copyrights.
Libpeony is based on gvfs/gio, and build with Qt5. You can see more infomation from the project Peony.
To build and run these project, you have to install the libpeony and its development files into your system.
sudo apt install libpeony-dev
see the peony's chapter build-from-source-and-test
To make sure the healthy and long-term growth of Peony, we choose publish it under GPLv3 and LGPLv3.
The modification of peony is allowed, but you must publish your changes, otherwise you will violate the GPLv3.
The modification of libpeony is allowed, but you must publish your changes, otherwise you will violate the LGPLv3.
The second development based on libpeony has not limitted. You can reserve the changes and make it private.