If you have Clementin music player installed (version 1.0) you can see that global menu support is disabled.
To enable it you need to update to latest version of Clementin.
This is because of bug with global menu and QT applications. Now when this bug is fixed you can have global menu support enabled again.
sudo add-apt-repository ppa:me-davidsansome/clementine-dev
sudo apt-get update
sudo apt-get upgrade