system/classes/Validate.php
public function setSelect($name, $value, $default = false)
    {
        if (isset($this->data[$name])) {
            if ($this->data[$name] == $value) {
                return 'selected';
            }
            else {
                return '';
            }
        }
        else {
            if ($default) {
                return 'selected';
            }
            else {
                return '';
            }
        }
    }
public function setSelect($name, $value, $default = false)
    {
        if (isset($this->data[$name])) {
            if ($this->data[$name] == $value) {
                return 'selected';
            }
            else {
                return '';
            }
        }
        else {
            if ($default) {
                return 'selected';
            }
            else {
                return '';
            }
        }
    }
For resetting a form Select's data after a failed validation.
$name = Select's name
$value = Option's value
$default = whether this Option should be selected by default.