Gtk.TextIter.prototype.backward_word_start

function backward_word_start():Boolean {
    // Gjs wrapper for gtk_text_iter_backward_word_start()
}

Moves backward to the previous word start. (If iter is currently on a word start, moves backward to the next one after that.) Word breaks are determined by Pango and should be correct for nearly any language (if not, the correct fix would be to the Pango word break algorithms).