De acordo com este arquivo de esquema da página do Linux Mint GitHub:
<key name="greeter-export" type="b">
<default>true</default>
<summary>Whether or not to export the currently playing song to the greeter.</summary>
<description>
If enabled the sound indicator will export the current player and
song to the greeter so that it can be shown if the user is selected
and the sound menu is shown.
</description>
</key>
<key name="global-mute" type="b">
<default>false</default>
<summary>Initial setting for global mute (mute all) on the menu </summary>
<description>
On start up volume should not be muted.
</description>
</key>
Eu sou bastante fonte da Canonical ter as fontes postadas em algum lugar on-line, mas as fontes do Linux Mint são suficientes para nossos propósitos.