You don't need to read this document to use SingleWindow. There's no further instructions, but it can help to address what brought you here. In short:
SwiftUI/ MacOS doesn’t easily enable the window behavior of common mac apps like iTunes or Calendar, where you could close the window and retrieve it with Cmd-0.
SingleWindow offers
- access to NSWindow
- program control to open a window without needing the swiftui environment variable openWindow, which requires an already existing View
- full screen zoom, not enabled with Window() Scene.
- access to the Window's stylemask - to enable/disable zoom, .closable, .miniaturizable, etc
- .isOpen - Easy factual app knowledge of whether the window is actually open. Many (unreliable) housekeeping functions tied to .onAppear() can be replaced.
- External monitor support
- Ability to identify the front window, needed for handling menu commands.
- does not save/restore window states across app launch. Your app could easily do this, and I may add the option in the future. But Swiftui's window state restoration gives the app no possibility of control. I don't always want my app to restore the windows.
- Having exactly one - Using Window() Scene allows multiple, and very difficult to enforce this.
- WindowDelegate functions
(I worked really hard not to make this a rant. how'd i do?)