macOS: center window title when titlebar tabs enabled

Uses a custom toolbar that populates itself with a centered text field and provides a method to set the text.

macos/Ghostty.xcodeproj/project.pbxproj

@@ -65,6 +65,7 @@
 		A5E112952AF73E8A00C6E0C2 /* ClipboardConfirmationController.swift in Sources */ = {isa = PBXBuildFile; fileRef = A5E112942AF73E8A00C6E0C2 /* ClipboardConfirmationController.swift */; };
 		A5E112972AF7401B00C6E0C2 /* ClipboardConfirmationView.swift in Sources */ = {isa = PBXBuildFile; fileRef = A5E112962AF7401B00C6E0C2 /* ClipboardConfirmationView.swift */; };
 		A5FEB3002ABB69450068369E /* main.swift in Sources */ = {isa = PBXBuildFile; fileRef = A5FEB2FF2ABB69450068369E /* main.swift */; };
+		AEF9CE242B6AD07A0017E195 /* TerminalToolbar.swift in Sources */ = {isa = PBXBuildFile; fileRef = AEF9CE232B6AD07A0017E195 /* TerminalToolbar.swift */; };
 		C159E81D2B66A06B00FDFE9C /* OSColor+Extension.swift in Sources */ = {isa = PBXBuildFile; fileRef = C159E81C2B66A06B00FDFE9C /* OSColor+Extension.swift */; };
 		C159E89D2B69A2EF00FDFE9C /* OSColor+Extension.swift in Sources */ = {isa = PBXBuildFile; fileRef = C159E81C2B66A06B00FDFE9C /* OSColor+Extension.swift */; };
 /* End PBXBuildFile section */
@@ -125,6 +126,7 @@
 		A5E112942AF73E8A00C6E0C2 /* ClipboardConfirmationController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ClipboardConfirmationController.swift; sourceTree = "<group>"; };
 		A5E112962AF7401B00C6E0C2 /* ClipboardConfirmationView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ClipboardConfirmationView.swift; sourceTree = "<group>"; };
 		A5FEB2FF2ABB69450068369E /* main.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = main.swift; sourceTree = "<group>"; };
+		AEF9CE232B6AD07A0017E195 /* TerminalToolbar.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = TerminalToolbar.swift; sourceTree = "<group>"; };
 		C159E81C2B66A06B00FDFE9C /* OSColor+Extension.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "OSColor+Extension.swift"; sourceTree = "<group>"; };
 /* End PBXFileReference section */
 
@@ -281,6 +283,7 @@
 				A5D0AF3A2B36A1DE00D21823 /* TerminalRestorable.swift */,
 				A596309D2AEE1D6C00D64628 /* TerminalView.swift */,
 				A51B78462AF4B58B00F3EDB9 /* TerminalWindow.swift */,
+				AEF9CE232B6AD07A0017E195 /* TerminalToolbar.swift */,
 				A535B9D9299C569B0017E2E4 /* ErrorView.swift */,
 			);
 			path = Terminal;
@@ -493,6 +496,7 @@
 				A5E112952AF73E8A00C6E0C2 /* ClipboardConfirmationController.swift in Sources */,
 				8503D7C72A549C66006CFF3D /* FullScreenHandler.swift in Sources */,
 				A596309E2AEE1D6C00D64628 /* TerminalView.swift in Sources */,
+				AEF9CE242B6AD07A0017E195 /* TerminalToolbar.swift in Sources */,
 				C159E81D2B66A06B00FDFE9C /* OSColor+Extension.swift in Sources */,
 				A5CEAFDE29B8058B00646FDA /* SplitView.Divider.swift in Sources */,
 				A5E112972AF7401B00C6E0C2 /* ClipboardConfirmationView.swift in Sources */,

macos/Sources/Features/Terminal/TerminalController.swift

@@ -482,7 +482,13 @@ class TerminalController: NSWindowController, NSWindowDelegate,
     }
     
     func titleDidChange(to: String) {
-        self.window?.title = to
+        guard let window = window as? TerminalWindow else { return }
+        
+        window.title = to
+        
+        // Custom toolbar-based title used when titlebar tabs are enabled.
+        guard let toolbar = window.toolbar as? TerminalToolbar else { return }
+        toolbar.setTitleText(to)
     }
     
     func cellSizeDidChange(to: NSSize) {

macos/Sources/Features/Terminal/TerminalToolbar.swift

@@ -0,0 +1,44 @@
+// Custom NSToolbar subclass that displays a centered window title,
+// in order to accommodate the titlebar tabs feature.
+
+import Foundation
+import Cocoa
+import SwiftUI
+
+class TerminalToolbar: NSToolbar, NSToolbarDelegate {
+	static private let TitleIdentifier = NSToolbarItem.Identifier("TitleText")
+	private let TitleTextField = NSTextField(
+		labelWithString: "👻 Ghostty"
+	)
+	
+	func setTitleText(_ text: String) {
+		self.TitleTextField.stringValue = text
+	}
+	
+	override init(identifier: NSToolbar.Identifier) {
+		super.init(identifier: identifier)
+		delegate = self
+		if #available(macOS 13.0, *) {
+			centeredItemIdentifiers.insert(Self.TitleIdentifier)
+		} else {
+			centeredItemIdentifier = Self.TitleIdentifier
+		}
+	}
+	
+	func toolbar(_ toolbar: NSToolbar, itemForItemIdentifier itemIdentifier: NSToolbarItem.Identifier, willBeInsertedIntoToolbar flag: Bool) -> NSToolbarItem? {
+		guard itemIdentifier == Self.TitleIdentifier else { return nil }
+		
+		let toolbarItem = NSToolbarItem(itemIdentifier: itemIdentifier)
+		toolbarItem.isEnabled = true
+		toolbarItem.view = self.TitleTextField
+		return toolbarItem
+	}
+	
+	func toolbarAllowedItemIdentifiers(_ toolbar: NSToolbar) -> [NSToolbarItem.Identifier] {
+		return [Self.TitleIdentifier]
+	}
+	
+	func toolbarDefaultItemIdentifiers(_ toolbar: NSToolbar) -> [NSToolbarItem.Identifier] {
+		return [Self.TitleIdentifier]
+	}
+}

macos/Sources/Features/Terminal/TerminalWindow.swift

@@ -42,8 +42,12 @@ class TerminalWindow: NSWindow {
             // so we make sure it's the right size/position, and exists.
             self.toolbarStyle = .unifiedCompact
             if (self.toolbar == nil) {
-                self.toolbar = NSToolbar(identifier: "Toolbar")
+                self.toolbar = TerminalToolbar(identifier: "Toolbar")
             }
+            // We directly hide the view containing the title text because if we use the
+            // `titleVisibility` property for this it prevents the window from hiding the
+            // tab bar when we get down to a single tab.
+            self.hideTitleText()
         } else {
             // "expanded" places the toolbar below the titlebar, so setting this style and
             // removing the toolbar ensures that the titlebar will be the default height.
@@ -62,6 +66,21 @@ class TerminalWindow: NSWindow {
         titlebarContainer.layer?.backgroundColor = color
     }
     
+    // Directly hide the view containing the title text
+    func hideTitleText() {
+        guard let toolbarTitleView = contentView?.superview?.subviews.first(where: {
+            $0.className == "NSTitlebarContainerView"
+        })?.subviews.first(where: {
+            $0.className == "NSTitlebarView"
+        })?.subviews.first(where: {
+            $0.className == "NSToolbarView"
+        })?.subviews.first(where: {
+            $0.className == "NSToolbarTitleView"
+        }) else { return }
+        
+        toolbarTitleView.isHidden = true
+    }
+    
     // This is called by macOS for native tabbing in order to add the tab bar. We hook into
     // this, detect the tab bar being added, and override its behavior.
     override func addTitlebarAccessoryViewController(_ childViewController: NSTitlebarAccessoryViewController) {
@@ -74,7 +93,8 @@ class TerminalWindow: NSWindow {
             // Ensure it has the right layoutAttribute to force it next to our titlebar
             childViewController.layoutAttribute = .right
             
-            // Hide the title text if the tab bar is showing since we show it in the tab
+            // If we don't set titleVisibility to hidden here, the toolbar will display a
+            // "collapsed items" indicator which interferes with the tab bar.
             titleVisibility = .hidden
             
             // Mark the controller for future reference so we can easily find it. Otherwise
@@ -90,9 +110,9 @@ class TerminalWindow: NSWindow {
     }
     
     override func removeTitlebarAccessoryViewController(at index: Int) {
-        let childViewController = titlebarAccessoryViewControllers[index]
+        let isTabBar = titlebarAccessoryViewControllers[index].identifier == Self.TabBarController
         super.removeTitlebarAccessoryViewController(at: index)
-        if (childViewController.identifier == Self.TabBarController) {
+        if (isTabBar) {
             hideCustomTabBarViews()
         }
     }
@@ -104,9 +124,6 @@ class TerminalWindow: NSWindow {
         
         // Hide the window drag handle.
         windowDragHandle?.isHidden = true
-        
-        // Enable the window title text.
-        titleVisibility = .visible
     }
     
     private func pushTabsToTitlebar(_ tabBarController: NSTitlebarAccessoryViewController) {