Mixer Uses Default Configuration For Each Session
At the beginning of every Musescore session, the Mixer content and size appear to be determined by mostly “built in parameters”. In my particular application I use both the slider and MIDI sections so the default configuration for Musescore versions prior to 3.6 served me fairly well.
With version 3.6 that is no longer the case. First the MIDI section was omitted #315408: Mixer panel not shown correct when opened. That was corrected in version 3.6.2 but, on my computer, at the expense of a Slider section so small that there are actually no individual sliders available.
After reviewing many of the reported Mixer “problems”, it appears that each person’s ideal mixer configuration is sufficiently unique that no “default” mixer configuration would ever be completely satisfactory. While the mixer size and content can be adjusted within a session, those adjustments do not carry over to succeeding sessions.
In the current Mixer, the content of the Slider section appears to be completely determined by the amount of space available to it; i.e. the dimensions of the Mixer window less the vertical space required for the MIDI section if it is present.
Given that, I propose saving the Mixer configuration (dimensions and MIDI section presence) as part of the score to serve as the starting Mixer configuration for the next session. While the “ideal” Mixer configuration would need to be established for each new score, that small, one time inconvenience would far outweigh the current constant annoyance of having to set the Mixer configuration for each session.