> update our subscription layer to call subscribers on the main thread instead I often do this, but have been doing it less frequently, lately, because I don't

> update our subscription layer to call subscribers on the main thread instead I often do this, but have been doing it less frequently, lately, because I don't want to force a thread switch, unless I know that I'll be calling UIKit functions (not always things that affect UI. Many "background" UIKit functions also require main thread). Instead, I clearly mention the thread state, in the API headerdoc description ("- parameter handler: A simple, no-parameter, tail completion. May be called in any thread.").