Menu Bar - Playback controls stay active when media players do not have the matching capability

[Mirsal Ennaime]

Capabilities like CanPlay, CanGoNext, CanGoPrev and CanControl are ignored by the sound menu, while they should be used in order to deactivate the relevant controls when the matching property of the org.mpris.MediaPlayer2.Player interface is set to false.

<https://wiki.ubuntu.com/SoundMenu#Playback_item>: "The playback item should be present if the player can be controlled externally (CanControl) ... The Back button should be sensitive whenever the player can seek (CanSeek) or go to a previous track (CanGoPrevious). And the Forward button should be sensitive whenever the the player can seek or go to a next track (CanGoNext)."

[Conor Curran (cjcurran)]

Thanks Mirsal, agreed. Please consider this design team for any future designs with regards the sound menu.

[Matthew Paul Thomas (mpt)]

Specification updated. <https://wiki.ubuntu.com/SoundMenu?action=diff&rev2=71&rev1=69> Unfortunately I can't tell, from the Mpris spec, whether the "CanGoNext" and "CanGoPrevious" properties change based on the current play state, or whether they're general properties of the player.

[Matthew Paul Thomas (mpt)]

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>