Gtk.TextIter.prototype.set_visible_line_index

function set_visible_line_index(byte_on_line:Number):void {
    // Gjs wrapper for gtk_text_iter_set_visible_line_index()
}

Like Gtk.TextIter.prototype.set_line_index, but the index is in visible bytes, i.e. text with a tag making it invisible is not counted in the index.