Bug 450937

SUMMARY
The "simple" version of the audio applet, where the options to change the playback device are hidden, makes it hard to set the right audio output when an external device is connected and disconnected, as described below.

STEPS TO REPRODUCE
1. Connect an external hdmi device with audio output. The audio applet shows two playback devices: "Laptop Speaker" and "HDMI Output".
2. Select HDMI Output as default or change playback output of a stream to HDMI in the "Applications" tab. Audio plays through the HDMI.
3. Disconnect HDMI.

OBSERVED RESULT
No audio can be heard, since output does not automatically switch back from HDMI to Speaker.
Moreover, the audio applet becomes "simple", as there is only one output, so the applet decides to hide the options to set the default device or switch the playback device in the application tab.
To fix the issue, I now have to open "Configure audio devices" to set the correct playback stream for an application. Also, I have to click on "Show inactive devices" before I can set the default back to "Speaker" again.

EXPECTED RESULT
I don't know if switching the default or playback stream of an application to "Speaker" automatically is the right solution. But perhaps the audio applet can continue to show the "advanced" options of selecting the default device or the corresponding options in the Applications tab as long as an inactive device is selected and only hide when none of the outputs is to an inactive device? 

SOFTWARE/OS VERSIONS
Operating System: Arch Linux
KDE Plasma Version: 5.24.80
KDE Frameworks Version: 5.92.0
Qt Version: 5.15.2
Kernel Version: 5.16.11-arch1-1 (64-bit)
Graphics Platform: X11

Audio Server Name: PulseAudio (on PipeWire 0.3.47)