Hi. I'm trying to make at patch that will let you select a grouptrack to fold/unfold (something that will make it possible to midimap fold/unfold groups). My plan is to first get all tracks, then use the is_foldable to check which one of the tracks that is group-tracks, and send these to a umenu item, so it's possible for me to choose which grouptracks i want to fold/unfold. My problem is that after finding the grouptracks, i can't find a way to combine these to a list before sending them to the umenu. I know this probably is a stupid problem, but I'm quite new to this, so it'a problem even if it's stupid.... I've thought about splitting "id" and the id-number, then use zl.stream on both before combining the two list with zl.lace. But that didn't work out since i have to know how many numbers to combine with zl.stream, before combining them. Hope anyone can help me with this problem.