what's the name of the program/app/daemon that "plays" music in rhythmbox when i try to quit it with close button?

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http://askubuntu.com – I'm using ubuntu 12.04 with gnome-shell and "mediaplayer-extension" from https://extensions.gnome.org/extension/55/. When i hit the close button on a music player, like rhythmbox 2.9x, it hides somewhere, but it keeps playing music in the background. But if i try to do the same on another distro, when I hit the close button, rhythmbox quits instantly. The question is: What's the program/app/daemon's name that "plays" music in background even if i try to quit rhythmbox (or any music player without a tray-icon) with "close" button? If i try to remove that program, will rhythmbox (or any music (HowTos)