How to make full size content view in SwiftUI for macOS

Issue #689

func applicationDidFinishLaunching(_ aNotification: Notification) {
    // extend to title bar
    let contentView = ContentView()
        // .padding(.top, 24) // can padding to give some space
        .edgesIgnoringSafeArea(.top)

    // specify fullSizeContentView
    window = NSWindow(
        contentRect: NSRect(x: 0, y: 0, width: 800, height: 600),
        styleMask: [.titled, .closable, .miniaturizable, .texturedBackground, .resizable, .fullSizeContentView],
        backing: .buffered, 
       defer: false
    )
    window.center()
    window.setFrameAutosaveName("My App")

    // window.title = ... // no title
    // window.toolbar = NSToolbar() // use toolbar if wanted. This triggers .unifiedTitleAndToolbar styleMask
    window.titlebarAppearsTransparent = true
    window.titleVisibility = .hidden // hide title
    window.backgroundColor = R.color.myBackgroundColor // set our preferred background color

    window.contentView = NSHostingView(rootView: contentView)
    window.makeKeyAndOrderFront(nil)
}

I have an issue where if I use HSplitView, some Button are not clickable until I drag the split view handle. The workaround is to use HStack with a Divider

Updated at 2020-11-03 05:21:50