public function renderFormElement()
{
$elm = new Zend_Form_Element_Multiselect($this->getName(), array('label' => $this->getLabel() . ':'));
$elm->setDescription($this->getDescription());
$elm->setMultiOptions($this->getOptions());
$elm->setValue($this->getValue());
$elm->setRequired($this->getRequired());
$elm->setAttrib('style', 'width:300px;height:100px');
return $elm;
}