According to Gtk/Notes there are two ways to program GtkD, one "Gtk2-style" and the other "Gtk3-encouraged-style". Yet, GtkDecoded and elsewhere seem to all use "Gtk2-style".

Is there any reason I should prefer one to the other?

Are there any good up-to-date books on GtkD? (Or on Gtk, but that are easy to understand in terms of D?)