I couldn't figure out how to do either one. So, after downloading, I simply open a Finder window with the update highlighted. I'll leave it up to the user to figure out the rest.

Turns out it has nothing to do with main.swift. I have a dictionary defined as dict : [ CGWindowID : NSWindow]. if you do dict.removeValue(forKey: key)?.close() this double deallocates the NSWindow if dict[key] was the last strong reference. Found this by instead of Run in Xcode, you do Profile and select Zombie and I found that this NSWindow reference count goes to -1. oops.

Nope, same crash as before....

Should have said "Status menu item" instead of "menu item". Regardless, changed main.swift to this: import Cocoa let app = NSApplication.shared let delegate = AppDelegate() withExtendedLifetime(delegate, {         app.delegate = delegate         app.run()         app.delegate = nil   }) seems to fix the occasional crash. This just forces a hard link to AppDelegate() so it doesn't get deallocated, apparently.

You can figure out which Desktops go with which Screens by comparing their CGRect (be careful, some CGRect has the vertical axis direction flipped- see https://entonos.com/index.php/2021/05/20/which-cgrect-was-that/). However, I have yet to figure out which Space corresponds to which Desktop (or vice versa). The best I've found is to ask CoreGraphics if a Desktop window is currently on screen. You then know that Desktop is on the current Space. Of course, you don't know which Space you're actually on.

There doesn't appear to be any public API to do this. Searching GitHub, there are some codes that do this, but they are using non-public API (e.g. using CGSCopyManagedDisplaySpaces)

let window : NSWindow? = nil ... window?.collectionBehavior = .canJoinAllSpaces // window will be in all Spaces window?.collectionBehavior = .moveToActiveSpace // when window is activated, move to active Space window?.collectionBehavior = .stationary // Expose doesn't affect window, so it stays visible and stationary, like the Desktop window window?.collectionBehavior = .managed // window participates in Spaces and Expose (i.e. normal window). there are other options....

Thanks for your response. https://feedbackassistant.apple.com/feedback/9824294 By definition the bug only occurs occasionally. Gave a link to the code and the line to comment out to get the problem to appear. Unfortunately, there is no deterministic way to reproduce.

One clue is when the code starts, it always captures the Desktop background images correctly. It seems to fail only when the NSWorkspace.activeSpaceDidChangeNotification is sent. Introducing a block for 0.25 seconds seems to insure the image capture succeeds. Would prefer a better option than blocking.