Oh, it's hidden in the collapsed Rationale: "Even when playback can generally be controlled, there may not always be a next track to move to." So, those properties should determine the sensitivity of the Back/Forward buttons, not their presence. Spec updated again. <https://wiki.ubuntu.com/SoundMenu?action=diff&rev2=72&rev1=71>
Oh, it's hidden in the collapsed Rationale: "Even when playback can generally be controlled, there may not always be a next track to move to." So, those properties should determine the sensitivity of the Back/Forward buttons, not their presence. Spec updated again. <https:/ /wiki.ubuntu. com/SoundMenu? action= diff&rev2= 72&rev1= 71>