Very sorry for my late reply… Easter holydays
Let me explain my use case and rationale for asking for this feature. Sorry for the lengthy elaboration that goes way past the subject of this thread, but I hope it might be useful! You might very well have a different direction for Dorico in mind and, in that case, I’ll adapt.
In an Ad libitum, free-meter, aleatoric section, things are, usually, not really meant to be rhythmically aligned… This, in it’s self, sadly, goes against the very thoughtful “metered” inner logic of Dorico (and most other score writing programs out there I think…) that you and your team are continuously trying to perfect! I might admit that such “chaotic” music is not really common enough to receive that much attention, but, if one takes into account fermatas, colla parte, independent solo cadenzas etc., the breaking of sync/meter, in it’s very basic form, is not that uncommon after all… (please allow me to make a related request for the ability to hide an individual fermata for these exact situations! Pretty please!! )
Established composers that have, in the past, used advanced aleatoric techniques (I’m thinking mainly of Lutosławski and Penderecki here) thought that in such sections, music aligned vertically isn’t necessarily played in sync and they use barlines, usually dotted, to loosely or strictly align their music. There are frequent situations where they want to clearly align just the start of a stream of otherwise unsynced musical lines and, for this purpose, they use, again, barlines (yes… downward arrows, footnote explanations etc., but still, conceptually, basic barlines…).
For my own “Ad libitum” sections I am using the same logic as I think it makes perfect sense, both musically, historically and in Dorico’s current internal logic. These are some “Ad libitum” principles that I’m thinking of and how they relate to Dorico:
Notes aligned do not necessarily play together. This can be easily done right now in Dorico, although, sometimes, it may be quite difficult because of automatic rhythmic alignements! There are several “proper workarounds” like using the triplet tool or moving notes in the Engrave workspace, but for a truly “proper” way of writing aleatoric music, I can imagine an Ad libitum button, a region perhaps or something similar that, in such regions/sections/measures etc., makes Dorico not align globally, rhythmically, but optically on a staff by staff basis… just a thought… It’s certainly not for me to decide what is proper and what’s not, but anyway, this can be done right now and it’s a workable solution! Thank you!
Notes placed immediately after a barline are in perfect sync (native logic in Dorico), which logically means that notes not immediately after the barline are a bit later, unsynced (easily done with hidden rests). OK… sometimes, a composer might want an instrument to play without syncing with others! Of course! That is the whole purpose of asynchronous music! In this case, that instrument might not have a barline when everybody else has one!! Trying this out in Dorico right now raises a problem: a global meter change (Ctrl+M then Enter) forces a global barline that interrupts/overrides any previous local meter change (Ctrl+M then Alt+Enter) and cannot be hidden. Well… one could make several local meter changes in a long bar and leave just one staff the full length, but it’s not a workable solution in a large orchestral setting (plus an annoyance regarding the numbering of measures that would take too much additional space to explain here)… Thus, the ability to hide a global barline on a single staff using an independent local barline is, in this case, very useful and, surely, an easy software implementation! Of course, there might be arguments against the practice of having a different number of bars/measures for each staff, I myself try to avoid this, but, sometimes, it is really the best musical solution and is extensively used in several works of the aforementioned authors!
Extensive use of strict repetition, variation, improvisation for which Dorico has already added the barline, custom line and text tools. A kind of footnote tool would be a great addition, but, right now, this can be done and that’s excelent! Thank you!