I would like to have the ability to show places where instruments playing freely / ametrically or playing difficult tuplets should line up using vertical lines. For instance, showing an accompanist where exactly I want them to coordinate a note’s attack with an soloist playing ametric music.
Ideally, this could be part of the cue-ing system, so that if this is occurring in a large ensemble setting there could be a vertical line from, for example, clarinet 2 through oboe two, with those lines and “[insert instrument here]” showing up on each part.
At minimum, though, an ability to show alignment with using a huge number of barlines would be great. Here’s an example. I’d like to be able to do this just by selecting the notes, rather than having to switch to engrave mode each time.