There's a really irritating thing in AC18 where you can open the issue history and create a New Issue, then add/ remove drawings for issue, set all the issue information and then you can't save it because you haven't reserved the Book Settings
PLEASE PLEASE PLEASE put Reserve buttons in sensible places. There needs to be a reserve button the issue history so one can reserve the Book settings without having to re-do your issue information. There are quite a few instances of Reserve buttons in ArchiCAD not being in the dialogue in which you've opened which means losing time re-doing something because you haven't reserved it.
I'm clearly not the only person experiencing this :