Thank you for you answer. Actually, following the instruction (how to build from the source), i also installed qt5, with the installer here:
http://download.qt-project.org/offic...86-offline.run
But i don't know if doing both was wise. But i did that first, trying to build from source, and then, i tryed to reinstall the repository version, after installing qt5*
When asking wich version of qt is running, it says 5.