Formo 1.1.x multiple select driver

mselect.php

<?php defined('SYSPATH') or die('No direct script access.');

Formo::include_file('driver', 'select');

class Formo_mselect_Driver extends Formo_select_Driver {
	public $selected_values = array();
	
	public function __construct($name='',$info=array()) {
		parent::__construct($name,$info);
		
		if(count($this->selected_values) == 0 && !empty($this->value)) {
			$this->selected_values = array($this->value);
		}
	}
	
	public function add_post() {
		$form = Formo::instance($this->formo_name);
		$type = $form->_post_type;
		
		$strippedName = substr($this->name, 0, strlen($this->name) - 2); // strip off the []
		$this->selected_values = Input::instance()->$type($strippedName);
		
		if(empty($this->selected_values)) {
			$this->selected_values = array();
		}
	}
	
	public function render() {
		$sel= '<select name="'.$this->name.'"'.Formo::quicktagss($this->_find_tags())." multiple=\"multiple\">"."\n";
		foreach ($this->values as $k=>$v) {
			$k = preg_replace('/_[bB][lL][aA][nN][kK][0-9]*_/','',$k);
			$selected = in_array($v, $this->selected_values) ? " selected='selected'" : '';
			$sel .= "\t\t".'<option value="'.$v.'"'.$selected.'>'.$k.'</option>'."\n";
		}
		$sel.= "</select>";	
		return $sel;
	}
	
	protected function validate_this() {
		if(empty($this->selected_values)) {
			return $this->error = $this->required_msg;
		}
	}
}