It should be fairly straightforward to define a command to operate on unbroken/broken stacks of ties, and I can look into this.
It is not possible to modify shapes of ties or slurs by changing the control-points property if there are multiple ties or slurs at the same musical moment – the \tweak command will also not work in this case. However, the tie-configuration property of TieColumn can be overridden to set start line and direction as required.
That's unfortunate :(
2. In the development version warnings were given and a color was used to indicate a mismatch of offset count and number of curves in a broken one. What is the reason to not include that into the release?
My thinking here was to get the basic functionality into the code base, and these warnings are helpful but not strictly necessary. (They were designed to be part of a slur-editing tool and might be more suitable for now as an enhancement on the LSR--opinions welcome!)
That sounds reasonable. But probably there is room for a "backdoor" to switch it on or plug in some kind of callback - a context property(?) - so there's no need to copy the whole function to LSR - now that it's already in the codebase ;-) ... just a thought.
I'll have to think about this some. The issue I see is that the version which reports mismatches depends on the location argument of the music function for the error message.
For now, thanks again for this amazing helper :-)
You're very welcome! Thanks to everybody who helped get it to this stage!
Best,
David