Pickup measures show wrong rests when the Actual duration is modified

[cadiz2]

Issue type

UX/Interaction bug (incorrect behaviour)

Description with steps to reproduce

1. New score for Flute, Time signature 4/4, with a pickup measure (1/4) created with the Wizard.

2. Create two more incomplete measures (Actual duration : 1/4 and 1/8) in the following measures

   Expected result: display of a quarter rest (as when creating the score) and a 8th rest

• Works as expected with 4.3.2
• Malfunctions as of version 4.4.0 (See GIF below)

Supporting files, videos and screenshots

What is the latest version of MuseScore Studio where this issue is present?

4.4.0

Regression

Yes, this used to work in a previous version of MuseScore 4.x

Operating system

Windows 10

Additional context

No response

Checklist

• [X] This report follows the guidelines for reporting bugs and issues
• [X] I have verified that this issue has not been logged before, by searching the issue tracker for similar issues
• [X] I have attached all requested files and information to this report
• [X] I have attempted to identify the root problem as concisely as possible, and have used minimal reproducible examples where possible

[oktophonie]

It it really a 'malfunction'? It seems just as likely that you might want a measure rest as you might want it to split into specific rests. After 'bar 0', bars with modified lengths are not likely to be pickup bars.

[cadiz2]

This is a very unexpected result:

1. Because I can't remember a previous version of MuseScore that didn't display the rest associated with the change in Actual Duration. And therefore confusing.
2. In addition, why should the behavior be different when creating the score with the wizard and when changing it once it's been created? It's inconsistent, and therefore wrong in my eyes.

[cbjeukendrup]

It looks like we'll need a way to let the user tell whether something is intended to be a pickup bar or not. Currently, some heuristic is used, but I doubt its validity. I believe this heuristic was changed in 4.4; that may or may not be related.

[MarcSabatella]

For more history about the pickup heuristic, see issue https://github.com/musescore/MuseScore/issues/22080 and the PR that closed it, https://github.com/musescore/MuseScore/pull/22083. I'm not so sure the change in how rests are shown by default in empty measures was carefully considered and any change might be just an unintentional side effect. Assuming this is indeed the PR that changed the behavior, which seems likely, but I'm not by any means sure about that either.