Native notehead extender lines for proportional notation

Your idea

A common modern notational technique in unmetred, proportional or free-time notation is the use of 'notehead extender lines'. These are lines that extend from an unstemmed notehead to indicate sustain, and are preferred to the standard rhythmic durational indications, which imply the presence of a metre and/or may give a false impression of duration.

Many composers such as Lachenmann, Haas, Brown, etc., use this notation. While it is currently possible to 'fake' this notation using lines, it gets very fiddly and cumbersome to add multiple such lines, and getting exactly the right spacing from the notehead, as well as exactly the right vertical position.

I would love for MuseScore to support this as a native option in Notehead properties. It would be a game changer for proportional notation.

The UI could be a simple checkbox: 'Notehead extender line' or something like that, which would create a new horizontal line object to the right of the notehead. This object could then be manually dragged to extend. (MuseScore would just need to keep track of this object and its endpoint.) You might also want to add an option in Settings for the line width and offset from the notehead.

The real benefit of this for the typesetter/composer would be that multiple extender lines could be created at once, making notations like the image below so much easier to create.

Problem to be solved

Lack of native support for a key proportional notation feature, that currently requires a 'hack' to implement.

Prior art

I don't think any other music typesetting app has implemented this, hence why it could make MuseScore really stand out as a serious alternative for contemporary composers.

Additional context

No response

Checklist

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Start by surveying MuseScore's Notehead properties and existing line objects, since the issue proposes a notehead option that creates a manually extendable horizontal line. Define the object’s spacing, vertical placement, width settings, persistence, and multi-selection behavior before implementation; done means proportional notation can be created natively without manually faking each line.