enable Mac native tabbing

src/App.zig

@@ -4,6 +4,7 @@
 const App = @This();
 
 const std = @import("std");
+const builtin = @import("builtin");
 const Allocator = std.mem.Allocator;
 const glfw = @import("glfw");
 const Window = @import("Window.zig");
@@ -12,6 +13,8 @@ const Config = @import("config.zig").Config;
 const BlockingQueue = @import("./blocking_queue.zig").BlockingQueue;
 const renderer = @import("renderer.zig");
 const font = @import("font/main.zig");
+const macos = @import("macos");
+const objc = @import("objc");
 
 const log = std.log.scoped(.app);
 
@@ -36,6 +39,21 @@ mailbox: *Mailbox,
 /// Set to true once we're quitting. This never goes false again.
 quit: bool,
 
+/// Mac settings
+darwin: if (Darwin.enabled) Darwin else void,
+
+/// Mac-specific settings
+pub const Darwin = struct {
+    pub const enabled = builtin.target.isDarwin();
+
+    tabbing_id: *macos.foundation.String,
+
+    pub fn deinit(self: *Darwin) void {
+        self.tabbing_id.release();
+        self.* = undefined;
+    }
+};
+
 /// Initialize the main app instance. This creates the main window, sets
 /// up the renderer state, compiles the shaders, etc. This is the primary
 /// "startup" logic.
@@ -52,9 +70,30 @@ pub fn create(alloc: Allocator, config: *const Config) !*App {
         .config = config,
         .mailbox = mailbox,
         .quit = false,
+        .darwin = if (Darwin.enabled) undefined else {},
     };
     errdefer app.windows.deinit(alloc);
 
+    // On Mac, we enable window tabbing
+    if (comptime builtin.target.isDarwin()) {
+        const NSWindow = objc.Class.getClass("NSWindow").?;
+        NSWindow.msgSend(void, objc.sel("setAllowsAutomaticWindowTabbing:"), .{true});
+
+        // Our tabbing ID allows all of our windows to group together
+        const tabbing_id = try macos.foundation.String.createWithBytes(
+            "dev.ghostty.window",
+            .utf8,
+            false,
+        );
+        errdefer tabbing_id.release();
+
+        // Setup our Mac settings
+        app.darwin = .{
+            .tabbing_id = tabbing_id,
+        };
+    }
+    errdefer if (comptime builtin.target.isDarwin()) app.darwin.deinit();
+
     // Create the first window
     try app.newWindow(.{});
 

src/Window.zig

@@ -32,7 +32,7 @@ const App = @import("App.zig");
 
 // Get native API access on certain platforms so we can do more customization.
 const glfwNative = glfw.Native(.{
-    .cocoa = builtin.os.tag == .macos,
+    .cocoa = builtin.target.isDarwin(),
 });
 
 const log = std.log.scoped(.window);
@@ -132,6 +132,14 @@ pub fn create(alloc: Allocator, app: *App, config: *const Config) !*Window {
     errdefer window.destroy();
     try Renderer.windowInit(window);
 
+    // On Mac, enable tabbing
+    if (comptime builtin.target.isDarwin()) {
+        const NSWindowTabbingMode = enum(usize) { automatic = 0, preferred = 1, disallowed = 2 };
+        const nswindow = objc.Object.fromId(glfwNative.getCocoaWindow(window).?);
+        nswindow.setProperty("tabbingMode", NSWindowTabbingMode.automatic);
+        nswindow.setProperty("tabbingIdentifier", app.darwin.tabbing_id);
+    }
+
     // Determine our DPI configurations so we can properly configure
     // font points to pixels and handle other high-DPI scaling factors.
     const content_scale = try window.getContentScale();