appkit:wait

(appkit:wait window)

Blocks the calling thread until the window is closed, polling twenty times a second, and answers nil. A script calls it last, because its process ends when the last form returns; the REPL does not need it. Never call it from a button's handler, which runs on the thread that would close the window. Part of the appkit package, a Cocoa widget layer written in rontolisp over objc and loaded on first use: macOS (java -jar, the rontolisp binary, or a compiled .class / .jar; never a .wasm), with a display. See the macOS GUI guide.

CL-USER> (appkit:wait *win*)   ; returns once the window is closed
NIL