apprt/gtk-ng: new window menu action

Not sure why I skipped this one, its super easy.

src/apprt/gtk-ng/class/window.zig

@@ -178,6 +178,7 @@ pub const Window = extern struct {
         const actions = .{
             .{ "about", actionAbout, null },
             .{ "close", actionClose, null },
+            .{ "new-window", actionNewWindow, null },
             .{ "copy", actionCopy, null },
             .{ "paste", actionPaste, null },
             .{ "reset", actionReset, null },
@@ -468,6 +469,14 @@ pub const Window = extern struct {
         self.as(gtk.Window).close();
     }
 
+    fn actionNewWindow(
+        _: *gio.SimpleAction,
+        _: ?*glib.Variant,
+        self: *Window,
+    ) callconv(.c) void {
+        self.performBindingAction(.new_window);
+    }
+
     fn actionCopy(
         _: *gio.SimpleAction,
         _: ?*glib.Variant,