The primary aim of the Gtk+2 panel project is to provide a panel that reuses whatever is available (if it is not overkill) in the obvious way, such as subclassing GtkWidget instead of implementing applets, or by using a GtkBuilder file instead of defining a new format to customize the panel. This approach gives some additional advantages for free: you can use common tools in uncommon ways. Above all, you can use Glade to design your own panel. All the dependencies apart from GTK+ are (and hopefully will be) optional.
xsettingsd is a daemon that implements the XSETTINGS specification. It is intended to be small, fast, and minimally dependent on other libraries. It can serve as an alternative to gnome-settings-daemon for users who are not using the GNOME desktop environment but who still run GTK+ applications and want to configure things such as themes, font antialiasing/hinting, and UI sound effects.