This is kmix kmix-4.14.1-1.2.x86_64 from openSUSE Factory with pulseaudio pulseaudio-5.0-6.3.x86_64 Reproducible: Always Steps to Reproduce: 1. Click on the KMix icon in the system tray 2. Drag the slider for master volume (left most) and increase or decrease the volume 3. Continue dragging Actual Results: The first drag tick causes the volume feedback (pop sound) to kick in. A new track "Volume change feedback" inserts itself on the right and seems to disturb the event queue. At this point if you continue dragging, nothing happens. If you release the mouse button, the kmix window disappears... Expected Results: Whenever tracks appear or disappear, dragging a volume slider should still be possible. The reason I'm using that slider is mostly because I want a finer-grained control of the volume.
It is also possible to trigger this behavior by playing temporary sounds: 1. On the command line, type: sleep 5; play /usr/share/sounds/KDE-Im-Nudge.ogg 2. During these 5 seconds, open kmix 3. Keep dragging any non-master slider (to not trigger the volume pop sound) 4. As soon as the sound from 1 plays, a new section appears 5. At this point dragging doesn't work any more
One idea to fix this would be to defer the insertion/deletion of pulseaudio controls while a drag operation is in progress. As soon as the user finished dragging, then insert/delete the control in question.
Note: the issue doesn't happen any more with: kmix5-14.12.3-1.1.x86_64 pulseaudio-6.0-2.1.x86_64 plasma5-workspace-5.3.0-66.1.x86_64
This is actually a downstream issue, caused by openSUSE's patch that removes the "Event Notification Volume" slider. The KF5 kmix package doesn't contain this patch any more, so it's fixed there. See also: https://bugzilla.opensuse.org/show_bug.cgi?id=896933
*** Bug 342572 has been marked as a duplicate of this bug. ***