Hi,
I see the project hasn't moved a lot those last years, and some patch presen't for a long time haven't been included yet.
Since PianoBooster won't stay in Debian unless ported to Qt5, I did such a port.
The source code is available here:
https://github.com/captnfab/PianoBoosterI imported the original svn repository (that's the "vanilla" branch), so all the commit history have been preserved.
I hope this will help the project to survive.
@Louis B.: If you don't have time to contribute to the source code anymore, I'd be happy to maintain it for a while, and help it survive Debian's migration to Qt5.