The blocking mode is not implemented on OSX Cocoa nor on the (deprecated) arsd.eventloop.
Added December 8, 2021 (dub v10.5)
Previously, this implementation was right inside eventLoop, but when I wanted to add the new BlockingMode parameter, the compiler got in a trouble loop so I just renamed it instead of adding as an overload. Besides, the new name makes it easier to remember the order and avoids ambiguity between two int-like params anyway.
This is the function eventLoop forwards to. It, in turn, forwards to EventLoop.get.run.