tag.php
protected function valueIsPossible($value)
    {
        $widgets = $this->getWidgets();
        for ($i = 0, $count = count($widgets); $i < $count; $i++) {
            if ($widgets[$i]->getAttribute('value') == $value) {
                return true;
            }
        }

        return false;
    }
protected function valueIsPossible($value)
    {
        $widgets = $this->getWidgets();
        for ($i = 0, $count = count($widgets); $i < $count; $i++) {
            if ($widgets[$i]->getAttribute('value') == $value) {
                return true;
            }
        }

        return false;
    }
Tests to see if a value is allowed.

@param string    Attempted value.

@return bool  True if a valid value.