[MU4 Issue] Parts can not be saved as individual MuseScore files

[henkdegroot]

Describe the bug
In MuseScore 3 it was possible to save a part as a separate/new musescore file. In MuseScore 4 this is no longer possible.

To Reproduce
Steps to reproduce the behavior:

1. Open a score with multiple instruments
2. Generate parts
3. Select a part tab (so you are looking at one of the parts)
4. Use the Save As option -> Save to computer

Expected behavior
The open part is saved as a new file. This file contains no other parts.

Additional context
We're not talking about PDFs here. We're talking about creating a separate MSCX / MSCZ file for each part.

It might be better to design a new save / export option that explicitly offers to save parts rather than rely on a hidden aspect of "Save as" behaviour.

[shoogle]

The code to save individual parts still exists for the --score-parts command line option, which can be used as follows:

mscore --score-parts Score.mscz | jq -j .partsBin[0] | base64 -d >Part.mscz

Sadly, MuseScore fails to load the resulting Part.mscz. If you extract, it the content of the file appears to be valid, but it doesn't quite conform to the new way score files are structured in MuseScore 4.

[SnyBr]

I've heard this functionality was originally removed because users complained that the whole score was not saved when you chose "save as" while happening to be working on a part at that moment. So perhaps a dedicated "save part as individual musescore file" option in addition to the normal "save as" could be considered.

[Jojo-Schmitz]

Came up again in https://musescore.org/en/node/366294