fix: begin implementation of suggested changes

src/Surface.zig

@@ -546,10 +546,8 @@ pub fn init(
         };
     }
 
-    if (config.fullscreen) {
-        if (@hasDecl(apprt.Surface, "toggleFullscreen")) {
-            rt_surface.toggleFullscreen(config.@"macos-non-native-fullscreen");
-        } else log.warn("runtime doesn't implement toggleFullscreen", .{});
+    if (config.title) |title| {
+        try self.rt_surface.setTitle(title);
     }
 }
 
@@ -670,16 +668,15 @@ pub fn handleMessage(self: *Surface, msg: Message) !void {
         .change_config => |config| try self.changeConfig(config),
 
         .set_title => |*v| {
+            // We ignore the message in case the title was set via config.
+            if (self.config.title) |_| {
+                return;
+            }
             // The ptrCast just gets sliceTo to return the proper type.
             // We know that our title should end in 0.
-            if (self.config.title) |title| {
-                log.debug("setting title \"{s}\"", .{title});
-                try self.rt_surface.setTitle(title);
-            } else {
-                const slice = std.mem.sliceTo(@as([*:0]const u8, @ptrCast(v)), 0);
-                log.debug("changing title \"{s}\"", .{slice});
-                try self.rt_surface.setTitle(slice);
-            }
+            const slice = std.mem.sliceTo(@as([*:0]const u8, @ptrCast(v)), 0);
+            log.debug("changing title \"{s}\"", .{slice});
+            try self.rt_surface.setTitle(slice);
         },
 
         .set_mouse_shape => |shape| {

src/apprt/gtk/App.zig

@@ -28,6 +28,7 @@ const UnsafePasteWindow = @import("UnsafePasteWindow.zig");
 const c = @import("c.zig");
 const inspector = @import("inspector.zig");
 const key = @import("key.zig");
+const testing = std.testing;
 
 const log = std.log.scoped(.gtk);
 
@@ -103,10 +104,36 @@ pub fn init(core_app: *CoreApp, opts: Options) !App {
     // Our app ID determines uniqueness and maps to our desktop file.
     // We append "-debug" to the ID if we're in debug mode so that we
     // can develop Ghostty in Ghostty.
+    const default_id = "com.mitchellh.ghostty";
     const app_id: [:0]const u8 = app_id: {
-        var id = config.class orelse "com.mitchellh.ghostty";
-        break :app_id if (builtin.mode == .Debug) "com.mitchellh.ghostty-debug" else id;
+        if (config.class) |class| {
+            break :app_id if (builtin.mode == .Debug) "com.mitchellh.ghostty-debug" else isValidGtkId(class) catch |err| switch (err) {
+                error.InvalidChar => {
+                    log.warn("Invalid char found in class. Setting app id to default value", .{});
+                    break :app_id default_id;
+                },
+                error.InvalidLength => {
+                    log.warn("Class name value is over 255 chars in length. Setting app id to default value", .{});
+                    break :app_id default_id;
+                },
+                error.NoDotInId => {
+                    log.warn("Class name has no dot char. Setting app id to default value", .{});
+                    break :app_id default_id;
+                },
+                error.StartWithDot => {
+                    log.warn("Class name start with dot. Setting app id to default value", .{});
+                    break :app_id default_id;
+                },
+                error.EndsWithDot => {
+                    log.warn("Class name ends with dot. Setting app id to default value", .{});
+                    break :app_id default_id;
+                },
+            };
+        } else {
+            break :app_id if (builtin.mode == .Debug) "com.mitchellh.ghostty-debug" else default_id;
+        }
     };
+
     // Create our GTK Application which encapsulates our process.
     log.debug("creating GTK application id={s} single-instance={}", .{
         app_id,
@@ -488,3 +515,54 @@ fn initMenu(self: *App) void {
 
     self.menu = menu;
 }
+
+fn isValidGtkId(app_id: [:0]const u8) ![:0]const u8 {
+    var position: u8 = 0;
+    var hasDot = false;
+
+    if (app_id.len > 255 or app_id.len == 0)
+        return error.InvalidLength;
+
+    if (app_id[position] == '.')
+        return error.StartWithDot;
+
+    if (app_id[app_id.len - 1] == '.')
+        return error.EndsWithDot;
+
+    while (true) {
+        const char = app_id[position];
+
+        switch (char) {
+            'a'...'z', 'A'...'Z', '0'...'9', '_', '-' => {
+                position += 1;
+                continue;
+            },
+            '.' => {
+                hasDot = true;
+                position += 1;
+                continue;
+            },
+            0 => {
+                if (position != app_id.len) return error.InvalidChar;
+                break;
+            },
+            else => return error.InvalidChar,
+        }
+    }
+
+    if (!hasDot) return error.NoDotInId;
+
+    return app_id;
+}
+
+test "ValidGtkClassName" {
+    try testing.expectEqualStrings("foo.bar", try isValidGtkId("foo.bar"));
+    try testing.expectEqualStrings("foo.bar.baz", try isValidGtkId("foo.bar.baz"));
+
+    try testing.expectError(error.NoDotInId, isValidGtkId("foo"));
+    try testing.expectError(error.InvalidChar, isValidGtkId("foo.bar?"));
+    try testing.expectError(error.EndsWithDot, isValidGtkId("foo."));
+    try testing.expectError(error.StartWithDot, isValidGtkId(".foo"));
+    try testing.expectError(error.InvalidLength, isValidGtkId(""));
+    try testing.expectError(error.InvalidLength, isValidGtkId("foo" ** 86));
+}

src/apprt/gtk/Window.zig

@@ -123,6 +123,10 @@ pub fn init(self: *Window, app: *App) !void {
     }
     c.gtk_box_append(@ptrCast(box), notebook_widget);
 
+    if (app.config.fullscreen) {
+        c.gtk_window_fullscreen(self.window);
+    }
+
     // All of our events
     _ = c.g_signal_connect_data(window, "close-request", c.G_CALLBACK(&gtkCloseRequest), self, null, c.G_CONNECT_DEFAULT);
     _ = c.g_signal_connect_data(window, "destroy", c.G_CALLBACK(&gtkDestroy), self, null, c.G_CONNECT_DEFAULT);