Couple of issues so far. HildonUIMode relies on custom built gtk3, something I'd rather avoid and probably isn't needed by GTK3 but will probably break some backwards compatibility. HildonSizeType I've copied into hildon-gtk.h as in my original port/Cordia. HILDON_SIZE_FULLSCREEN_WIDTH and HILDON_SIZE_HALFSCREEN_WIDTH will not work correctly with GTK3.

hildon-controlbar: initial port done except gtk_paint_box
hildon-seekbar: done, no big issues.
hildon-note: gtk_dialog_set_padding and one other function missing.
hildon-volumebar: current wip. Mostly done, just _realize and a few small fixes.