Call operator for objc.ObjCBlock<NSWindow? Function(ffi.Pointer<ffi.Void>, NSWindow)>.
objc.ObjCBlock<NSWindow? Function(ffi.Pointer<ffi.Void>, NSWindow)>
Available on ObjCBlock<NSWindow? Function(Pointer<Void>, NSWindow)>, provided by the ObjCBlock_NSWindow_ffiVoid_NSWindow_CallExtension extension