[usability] Unchecking mute in panel VolumeControl does not unmute in PulseAudio

[Guasong]

Running Lubuntu 15.10 live CD in Virtualbox

- install pavucontrol
- run pulseaudio
- click on Volume Control on the bottom right of the panel to show the panel volume control with its mute checkbox

In pavucontrol, tab Output devices:

- pushing the "mute audio" button in pavucontrol will check the Mute checkbox in panel volume control
- releasing the "mute audio" button in pavucontrol will uncheck the Mute checkbox in panel volume control
- checking the Mute checkbox in panel volume control will push the mute audio button in pavucontrol

However,

- unchecking the Mute checkbox in the panel volume control WILL NOT release the "mute audio" button in pavucontrol

Expected result:

- unchecking the Mute checkbox in the panel volume should release the "mute audio" button in pavucontrol.

**User expects to reverse the action of checking of the "mute" checkbox by unchecking the box.**

Moreover, as desired, pavucontrol empasizes that the audio is muted by rendering the volume scrollbar as "read only". It's grey and not modifiable. However the Volume control volume scrollbar of the panel stays editable and is not changed when the Mute checkbox is checked.

ProblemType: Bug
DistroRelease: Ubuntu 15.10
Package: lxpanel 0.8.1-1ubuntu2
ProcVersionSignature: Ubuntu 4.2.0-16.19-generic 4.2.3
Uname: Linux 4.2.0-16-generic x86_64
ApportVersion: 2.19.1-0ubuntu3
Architecture: amd64
CasperVersion: 1.365
Config_Home_Lubuntu:
 [Command]
 Logout=lxsession-default quit
CurrentDesktop: LXDE
Date: Sun Jan 3 14:31:56 2016
LiveMediaBuild: Lubuntu 15.10 "Wily Werewolf" - Release amd64 (20151021)
ProcEnviron:
 TERM=xterm
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: lxpanel
UpgradeStatus: No upgrade log present (probably fresh install)

[Guasong (musclorr)]

Reproduced with today's daily live of Xenial

--- This is what pulseaudio logs when checking the "Mute" button:
D: [alsa-sink-Intel ICH] alsa-sink.c: Read hardware volume: front-left: 65536 / 100% / 0.00 dB, front-right: 65536 / 100% / 0.00 dB
D: [pulseaudio] sink.c: The mute of sink alsa_output.pci-0000_00_05.0.analog-stereo changed from no to yes.
D: [alsa-sink-Intel ICH] alsa-sink.c: Requested to rewind 19188 bytes.
D: [alsa-sink-Intel ICH] alsa-sink.c: Limited to 18932 bytes.
D: [alsa-sink-Intel ICH] alsa-sink.c: before: 4733
D: [alsa-sink-Intel ICH] alsa-sink.c: after: 4733
D: [alsa-sink-Intel ICH] alsa-sink.c: Rewound 18932 bytes.
D: [alsa-sink-Intel ICH] sink.c: Processing rewind...
D: [alsa-sink-Intel ICH] sink.c: latency = 1731
D: [alsa-sink-Intel ICH] source.c: Processing rewind...
I: [pulseaudio] module-device-restore.c: Storing volume/mute for device+port sink:alsa_output.pci-0000_00_05.0.analog-stereo:analog-output;output-amplifier-on.
I: [pulseaudio] module-device-restore.c: Synced.

--- This is what is logged when unckecking the Mute button:

D: [alsa-sink-Intel ICH] alsa-sink.c: Read hardware volume: front-left: 29274 / 45% / -21.00 dB, front-right: 29274 / 45% / -21.00 dB
D: [alsa-sink-Intel ICH] alsa-sink.c: Read hardware volume: front-left: 29274 / 45% / -21.00 dB, front-right: 29274 / 45% / -21.00 dB

[Guasong (musclorr)]

--- This is what is logged when releasing the Mute button in pavucontrol:

D: [pulseaudio] protocol-native.c: Client pavucontrol changes mute of sink alsa_output.pci-0000_00_05.0.analog-stereo.
D: [pulseaudio] sink.c: The mute of sink alsa_output.pci-0000_00_05.0.analog-stereo changed from yes to no.
D: [alsa-sink-Intel ICH] alsa-sink.c: Requested to rewind 19188 bytes.
D: [alsa-sink-Intel ICH] alsa-sink.c: Limited to 18932 bytes.
D: [alsa-sink-Intel ICH] alsa-sink.c: before: 4733
D: [alsa-sink-Intel ICH] alsa-sink.c: after: 4733
D: [alsa-sink-Intel ICH] alsa-sink.c: Rewound 18932 bytes.
D: [alsa-sink-Intel ICH] sink.c: Processing rewind...
D: [alsa-sink-Intel ICH] sink.c: latency = 0
D: [alsa-sink-Intel ICH] source.c: Processing rewind...
I: [pulseaudio] module-device-restore.c: Storing volume/mute for device+port sink:alsa_output.pci-0000_00_05.0.analog-stereo:analog-output;output-amplifier-on.
I: [pulseaudio] module-device-restore.c: Synced.

I believe unchecking the mute button in the panel should trigger the same event.

[Guasong (musclorr)]

This issue disappear when restarting lightdm.

I suppose LXQtVolume::settingsChanged(), which is called when constructing the volume bar, is not called when pulseaudio is started. Therefore the previous engine is kept even when pulseaudio is available.

[Chris Guiver (guiverc)]

Thank you for reporting this bug to Ubuntu.

Ubuntu 15.10 (wily) reached end-of-life on July 28, 2016.

See this document for currently supported Ubuntu releases:
https://wiki.ubuntu.com/Releases

We appreciate that this bug may be old and you might not be interested in discussing it any more. But if you are then please upgrade to the latest Ubuntu version and re-test. If you then find the bug is still present in the newer Ubuntu version, please add a comment here telling us which new version it is in.

[Launchpad Janitor (janitor)]

[Expired for lxpanel (Ubuntu) because there has been no activity for 60 days.]