Don't use a toolbar for the traditional title/tab bar

I forgot I can use a `NSTitlebarAccessoryViewController` to house the
button

macos/Assets.xcassets/ResetZoom.imageset/Contents.json

@@ -0,0 +1,15 @@
+{
+  "images" : [
+    {
+      "filename" : "ResetZoom.pdf",
+      "idiom" : "universal"
+    }
+  ],
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  },
+  "properties" : {
+    "template-rendering-intent" : "template"
+  }
+}

macos/Sources/Features/Terminal/TerminalToolbar.swift

@@ -15,8 +15,6 @@ class TerminalToolbar: NSToolbar, NSToolbarDelegate {
         }
     }
 
-    var hasTitle: Bool = false
-
     override init(identifier: NSToolbar.Identifier) {
         super.init(identifier: identifier)
         
@@ -54,24 +52,6 @@ class TerminalToolbar: NSToolbar, NSToolbarDelegate {
             item.isEnabled = true
         case .resetZoom:
             item = NSToolbarItem(itemIdentifier: .resetZoom)
-
-            let view = NSView(frame: NSRect(x: 0, y: 0, width: 20, height: 20))
-            view.translatesAutoresizingMaskIntoConstraints = false
-            view.widthAnchor.constraint(equalToConstant: 20).isActive = true
-            view.heightAnchor.constraint(equalToConstant: 20).isActive = true
-            
-            let button = NSButton(image: NSImage(systemSymbolName: "arrow.down.right.and.arrow.up.left.square.fill", accessibilityDescription: nil)!, target: nil, action: #selector(TerminalController.splitZoom(_:)))
-
-            button.frame = view.bounds
-            button.isBordered = false
-            button.contentTintColor = .controlAccentColor
-            button.state = .on
-            button.imageScaling = .scaleProportionallyUpOrDown
-			button.allowsExpansionToolTips = true
-			button.toolTip = "Reset Zoom"
-            view.addSubview(button)
-
-            item.view = view
         default:
             item = NSToolbarItem(itemIdentifier: itemIdentifier)
         }
@@ -88,11 +68,7 @@ class TerminalToolbar: NSToolbar, NSToolbarDelegate {
         // getting smaller than the max size so starts clipping. Lucky for us, two of the
         // built-in spacers plus the un-zoom button item seems to exactly match the space
         // on the left that's reserved for the window buttons.
-        if hasTitle {
 		return [.titleText, .flexibleSpace, .space, .space, .resetZoom]
-        } else {
-            return [.flexibleSpace, .resetZoom]
-        }
     }
 }
 

macos/Sources/Features/Terminal/TerminalWindow.swift

@@ -15,29 +15,26 @@ class TerminalWindow: NSWindow {
         }
     }
 
-    private var resetZoomToolbarButton: NSButton? {
-        guard let button = toolbar?.items.first(where: { $0.itemIdentifier == .resetZoom })?.view?.subviews.first as? NSButton
-        else { return nil }
+    private lazy var resetZoomToolbarButton: NSButton = generateResetZoomButton()
 
-        return button
-    }
+    private lazy var resetZoomTabButton: NSButton = generateResetZoomButton()
 
-    private let resetZoomTabButton: NSButton = {
-        let button = NSButton()
-        button.target = nil
-        button.action = #selector(TerminalController.splitZoom(_:))
-        button.translatesAutoresizingMaskIntoConstraints = false
-        button.widthAnchor.constraint(equalToConstant: 20).isActive = true
-        button.heightAnchor.constraint(equalToConstant: 20).isActive = true
-        button.isBordered = false
-		button.allowsExpansionToolTips = true
-		button.toolTip = "Reset Zoom"
-        button.contentTintColor = .controlAccentColor
-        button.state = .on
-        button.image = NSImage(systemSymbolName: "arrow.down.right.and.arrow.up.left.square.fill", accessibilityDescription: nil)!
-            .withSymbolConfiguration(NSImage.SymbolConfiguration(scale: .large))
+	private lazy var resetZoomTitlebarAccessoryViewController: NSTitlebarAccessoryViewController? = {
+		guard let titlebarContainer = contentView?.superview?.subviews.first(where: { $0.className == "NSTitlebarContainerView" }) else { return nil }
 
-        return button
+		let size = NSSize(width: titlebarContainer.bounds.height, height: titlebarContainer.bounds.height)
+		let view = NSView(frame: NSRect(origin: .zero, size: size))
+
+		let button = generateResetZoomButton()
+		button.frame.origin.x = size.width/2 - button.bounds.width/2
+		button.frame.origin.y = size.height/2 - button.bounds.height/2
+		view.addSubview(button)
+
+		let titlebarAccessoryViewController = NSTitlebarAccessoryViewController()
+		titlebarAccessoryViewController.view = view
+		titlebarAccessoryViewController.layoutAttribute = .right
+
+		return titlebarAccessoryViewController
 	}()
 
     private lazy var keyEquivalentLabel: NSTextField = {
@@ -50,10 +47,10 @@ class TerminalWindow: NSWindow {
 
     private lazy var bindings = [
         observe(\.surfaceIsZoomed, options: [.initial, .new]) { [weak self] window, _ in
-            guard let resetZoomToolbarButton = self?.resetZoomToolbarButton, let tabGroup = self?.tabGroup else { return }
+            guard let tabGroup = self?.tabGroup else { return }
 
             self?.resetZoomTabButton.isHidden = !window.surfaceIsZoomed
-            self?.updateResetZoomToolbarButtonVisibility()
+            self?.updateResetZoomTitlebarButtonVisibility()
         },
 
         observe(\.keyEquivalent, options: [.initial, .new]) { [weak self] window, _ in
@@ -77,6 +74,8 @@ class TerminalWindow: NSWindow {
     override func awakeFromNib() {
         super.awakeFromNib()
 
+		_ = bindings
+
         // By hiding the visual effect view, we allow the window's (or titlebar's in this case)
         // background color to show through. If we were to set `titlebarAppearsTransparent` to true
         // the selected tab would look fine, but the unselected ones and new tab button backgrounds
@@ -95,9 +94,9 @@ class TerminalWindow: NSWindow {
         stackView.spacing = 3
         tab.accessoryView = stackView
 
+		if titlebarTabs {
 			generateToolbar()
-
-        _ = bindings
+		}
     }
 
     deinit {
@@ -118,7 +117,7 @@ class TerminalWindow: NSWindow {
         updateNewTabButtonOpacity()
         resetZoomTabButton.isEnabled = true
         resetZoomTabButton.contentTintColor = .controlAccentColor
-        resetZoomToolbarButton?.contentTintColor = .controlAccentColor
+        resetZoomToolbarButton.contentTintColor = .controlAccentColor
     }
 
     override func resignKey() {
@@ -127,13 +126,13 @@ class TerminalWindow: NSWindow {
         updateNewTabButtonOpacity()
         resetZoomTabButton.isEnabled = false
         resetZoomTabButton.contentTintColor = .labelColor
-        resetZoomToolbarButton?.contentTintColor = .tertiaryLabelColor
+        resetZoomToolbarButton.contentTintColor = .tertiaryLabelColor
     }
 
     override func update() {
         super.update()
 
-        updateResetZoomToolbarButtonVisibility()
+        updateResetZoomTitlebarButtonVisibility()
 
         titlebarSeparatorStyle = tabbedWindows != nil && !titlebarTabs ? .line : .none
 
@@ -204,13 +203,23 @@ class TerminalWindow: NSWindow {
         newTabButtonImageView.alphaValue = isKeyWindow ? 1 : 0.5
     }
 
-    private func updateResetZoomToolbarButtonVisibility() {
-        guard let resetZoomToolbarButton = resetZoomToolbarButton, let tabGroup else { return }
+    private func updateResetZoomTitlebarButtonVisibility() {
+        guard let tabGroup, let resetZoomTitlebarAccessoryViewController else { return }
 
-        if tabGroup.isTabBarVisible {
-            resetZoomToolbarButton.isHidden = true
+		let isHidden = tabGroup.isTabBarVisible ? true : !surfaceIsZoomed
+
+		if titlebarTabs {
+			resetZoomToolbarButton.isHidden = isHidden
+
+			for (index, vc) in titlebarAccessoryViewControllers.enumerated() {
+				guard vc == resetZoomTitlebarAccessoryViewController else { return }
+				removeTitlebarAccessoryViewController(at: index)
+			}
 		} else {
-            resetZoomToolbarButton.isHidden = !surfaceIsZoomed
+			if !titlebarAccessoryViewControllers.contains(resetZoomTitlebarAccessoryViewController) {
+				addTitlebarAccessoryViewController(resetZoomTitlebarAccessoryViewController)
+			}
+			resetZoomTitlebarAccessoryViewController.view.isHidden = isHidden
 		}
     }
 
@@ -220,11 +229,34 @@ class TerminalWindow: NSWindow {
     // isn't possible.
     private func generateToolbar() {
         let terminalToolbar = TerminalToolbar(identifier: "Toolbar")
-        terminalToolbar.hasTitle = titlebarTabs
 
         toolbar = terminalToolbar
         toolbarStyle = .unifiedCompact
-        updateResetZoomToolbarButtonVisibility()
+		if let resetZoomItem = terminalToolbar.items.first(where: { $0.itemIdentifier == .resetZoom }) {
+			resetZoomItem.view = resetZoomToolbarButton
+			resetZoomItem.view?.translatesAutoresizingMaskIntoConstraints = false
+			resetZoomItem.view?.widthAnchor.constraint(equalToConstant: 22).isActive = true
+			resetZoomItem.view?.heightAnchor.constraint(equalToConstant: 20).isActive = true
+		}
+        updateResetZoomTitlebarButtonVisibility()
+    }
+
+	private func generateResetZoomButton() -> NSButton {
+		let button = NSButton()
+		button.target = nil
+		button.action = #selector(TerminalController.splitZoom(_:))
+		button.isBordered = false
+		button.allowsExpansionToolTips = true
+		button.toolTip = "Reset Zoom"
+		button.contentTintColor = .controlAccentColor
+		button.state = .on
+		button.image = NSImage(named:"ResetZoom")
+		button.frame = NSRect(x: 0, y: 0, width: 20, height: 20)
+		button.translatesAutoresizingMaskIntoConstraints = false
+		button.widthAnchor.constraint(equalToConstant: 20).isActive = true
+		button.heightAnchor.constraint(equalToConstant: 20).isActive = true
+
+		return button
 	}
 
     // MARK: - Titlebar Tabs
@@ -233,9 +265,11 @@ class TerminalWindow: NSWindow {
     var titlebarTabs = false {
         didSet {
             self.titleVisibility = titlebarTabs ? .hidden : .visible
+			if titlebarTabs {
 				generateToolbar()
 			}
         }
+    }
     
     private var windowButtonsBackdrop: WindowButtonsBackdropView? = nil
     private var windowDragHandle: WindowDragView? = nil