AppKit application window in code

AppKit Application Menu.fs

        let editMenu =
            let undoMenuItem =
                let item = new NSMenuItem("Undo")
                item.KeyEquivalent <- "z"
                item.Action <- ObjCRuntime.Selector("undo:")
                item
            
            let redoMenuItem =
                let item = new NSMenuItem("Redo")
                item.KeyEquivalent <- "z"
                item.KeyEquivalentModifierMask <- NSEventModifierMask.ShiftKeyMask ||| NSEventModifierMask.CommandKeyMask
                item.Action <- ObjCRuntime.Selector("redo:")
                item
                
            let cutMenuItem =
                let item = new NSMenuItem("Cut")
                item.KeyEquivalent <- "x"
                item.Action <- ObjCRuntime.Selector("cut:")
                item
                
            let copyMenuItem =
                let item = new NSMenuItem("Copy")
                item.KeyEquivalent <- "c"
                item.Action <- ObjCRuntime.Selector("copy:")
                item
            
            let pasteMenuItem =
                let item = new NSMenuItem("Paste")
                item.KeyEquivalent <- "v"
                item.Action <- ObjCRuntime.Selector("paste:")
                item
                
            let item = new NSMenuItem()
            item.Title <- "Edit"
            item.Enabled <- true
            item.Submenu <- new NSMenu(Title = "Edit")
            item.Submenu.Items <- [|
                undoMenuItem
                redoMenuItem
                NSMenuItem.SeparatorItem
                cutMenuItem
                copyMenuItem
                pasteMenuItem
            |]
            item
        
        let appMenu =
            let quitMenuItem =
                let item = new NSMenuItem("Quit")
                item.KeyEquivalent <- "q"
                item.Action <- ObjCRuntime.Selector("terminate:")
                item
            
            let item = new NSMenuItem()
            item.Enabled <- true
            item.Title <- "App Name"
            item.Submenu <- new NSMenu()
            item.Submenu.Items <- [|
                quitMenuItem
            |]
            item
        
        let mainMenu = new NSMenu()
        mainMenu.AddItem appMenu
        mainMenu.AddItem editMenu
        
        let window = new UI.PreferencesWindow(appState)
        window.MakeKeyWindow()
        window.OrderFront(null)