What's the best choice of implementing the control of whether or not to show single-stave brackets when empty staves are hidden?
The current behaviour of MuseScore is not showing brackets which only span to a single stave if the user checks "Hide empty staves within systems". This behaviour can be wrong in many cases, such as orchestral notation, which normally has single-stave brackets.
The issue was raised in #296075: Allow user to choose whether or not hide brackets which span to a single staff when empty staves are hidden and has so far gained many replies. The simplest realization is to provide a checkbox controlling whether or not to show single-stave brackets. The downside of this design is that you have to toggle this checkbox for every score you want to change.
In one of the replies, Marc Sabatella offered a suggestion of implementation, which can provide the right result in most cases by specifying the transition point (default to 2 total instruments/staves (we'll have to choose one of them for specific implementation, but that's not the main point) in score) of the different behaviours: if a score has one or two instruments/staves, don't show single-stave brackets; if it has more than two instruments/staves, show single-stave brackets.
This indeed generates the right result in most cases, but also manifests a few problems:
The explanatory text for this option can be confusing. The shortest term that I can think of is "Show single-stave brackets if the total amount of instruments/staves exceeds: spin box". Besides being still very long, the main problem is that the relation between brackets and total amount of instruments/staves isn't easy to quickly understand. Anyone who's reading this post right now can understand, but what about unexperienced users? One thing is single-stave brackets, another thing is the total amount of instruments/staves;
The nature of this setting is ambiguous. This sounds more like a preference setting rather than a score style setting: in this score, there're only two instruments/staves, so don't show single-stave brackets; but in that score, there're more instruments/staves, so show single-stave brackets. It isn't intuitive to treat this kind of settings as a styling property for a single score;
This may not be something users would look for/notice. We, as humans, have more or less the tendency of skipping things that seem unrelated at first glimpse. If we want to find a control widget related to the visibility of single-stave brackets, it is beyond our intuition to look for a quantified setting instead of a simple checkbox.
I started (more precisely, continued) this discussion on the forum on Mr. Sabatella's recommendation. You're welcome to share your own opinion.