Ability to use letters and numbers with letters in measure numbers.

Your idea

In the "Measure properties" dialog, add a dropdown/radio group that toggles between numbers, letters, and numbers with letters as a way to count the measure.

Pictures below to illustrate the results expected.

Problem to be solved

This would immensely help in groups who practice "bar freezing" in pre-production and production.

Bar freezing is essentially freezing bar numbers in the first working version of a piece. So that in the next revision, whenever we cut or add measure numbers, old ones stay the same and the new ones get a new identifier to avoid confusion in fast paced rehearsal environments where revisions are coming in left and right.

Prior art

In Musescore (thankfully) I can do bar cuts where the piece jumps from one bar to another distant bar by using the "Measurement properties" dialog's "Add to measure number" input. I can cut bars and re-assign measure numbers as I please and it will automatically recount it for me. (Illustrated below, from a part from a piece made back in 2020).

And this feature already exists even back in the Musescore 3 days.

HOWEVER, there's lack of support for adding bars after a working version. This is where this feature request can come in and help. If MuseScore can have this letters in measure numbers feature, it would be great for fast moving rehearsal environments like ours.

Additional context

Once a piece is orchestrated, its first version is sent to rehearsals. Now, our rehearsal process goes through many stages, and in each stage we tend to cut and add measure numbers. And we do practice "bar freezing" - and I know a lot of other groups do this too, especially people on Broadway. This would be incredibly helpful not only for us but for other people as well.

Checklist

• This request follows the guidelines for reporting issues
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Start with the Measure properties dialog described in the issue and trace how measure numbers are currently configured and recounted. Define how the numbers, letters, and mixed-number modes should behave when measures are inserted or cut, then verify the result against the bar-freezing examples shown in the issue.