During testing of Xfce 4.12 as the new default desktop for Debian Edu (Skolelinux), it was discovered that the new audio mixer, the xfce4-pulse-plugin, is not enabled in the panel by default. The late xfce4-mixer was autostarted with the session. While this is not strictly a bug from a technical point of view, it pretty much upsets users if they cannot change the audio volume in the default config, and need to find out how to add plugins to the panel first.

Therefore, please add the PulseAudio plugin to the default panel config.