I use NSTexturedBackgroundWindowMask and isMovableByWindowBackground to provide a "unified" window interface so the user can drag a window by it's background (e.g. a large toolbar-like area at the top). Thats broken in 2019R1. I filed a feedback and was informed this was by design because Apple deprecated it in macOS 10.12 (it still works in 2018 R4 in my hands).
My question is, what is the modern API way to to allow this behavior? Unfortunately, the Apple docs don't give a clue and by google searches aren't helping.