So presently if you toggle the mute button, it incorrectly changes the volume slider to 100% and then changes it back to original volume level when you untoggle the mute button. When the volume slider moves to 100%, the volume slider can still be adjusted and then untoggling the mute button will keep the volume at that changed level.
I'd like to propose one of these two behaviors:
1) The volume slider not be changed when mute is toggled and modifying the volume slider when mute is enabled will untoggle mute. This is the behaviour of media players like vlc, smplayer, clementine, qmmp
2) The volume slider not be changed when mute is toggled and the volume slider be disable until the mute button is untoggled.
Please add keyword 'needsUXEval' and CC 'firstname.lastname@example.org' if input from UX is needed.