Bug 352457

A new report to avoid cluttering the related to bug report: https://bugs.kde.org/show_bug.cgi?id=352455 

With the phonon-gstreamer backend (version 4.8.2-1), sounds for system notifications may be played even if the user has muted the "Event Sounds" stream in KMix or vice versa: play back may be muted even if the stream was just unmuted.

Toggling mute/unmute on the "Event Sounds" stream has no effect on an already opened systemsettings. Notifications are either muted or unmuted according to "Event Sounds" state at start up of systemsettings, but **not** according to its current state at time of play back.

Reproducible: Always

Steps to Reproduce:
1. Open system settings
2. Toggle the mute state of the "Event Souds" stream in KMix to be opposite of whatever it was before starting system settings.
3. Trigger a notification sound, for example leaving a settings page when there are uncommitted changes to the configuration.

Actual Results:  
Observable behaviour for the gstreamer backend is different from the VLC one but still not completely correct. Adjusting volume appears to work, but muting/unmuting behaviour requires restarting open applications for the new settings of the "Event Sounds" stream to take effect.

A workaround is to slide the volume all the way down, instead of muting/unmuting but this is not exactly ideal.

Expected Results:  
I'd expect play back of event sounds to adhere strictly to settings for the "Event Sounds" stream at the time of play back (i.e. not at the time of opening the application). If the stream is muted this should properly override the audio volume setting because it is possible in pulseaudio to set a volume first and then mute the stream.