Magento: only existing countries in drop-down filter for "Country" column in Grid View - filter

Question

I have created a custom Grid View with the "Country" column:
$this->addColumn('ship_country', array(
'header' => $this->__('Country'),
'index' => 'countrycode',
'type' => 'country'
));
The collection list which is displayed in the grid has only 2 countries: Ireland and UK.
Problem: the Filter Header for country column shows the drop-down list with all possible, over 200, countries stored inside Magento.
Question: is it possible to force filter to show only Ireland and UK in the drop-down?
Like this:

Answer 1

I have solved this problem with the following code:
$this->addColumn('ship_country', array(
'header' => $this->__('Country'),
'index' => 'countrycode',
'type' => 'options',
'options' => Mage::helper('mymodule')->getCountries(),
));
Where Helper getCountries() method looks something like this:
public function getCountries() {
$collection = Mage::getModel('mymodule/entity')->getCollection();
$collection->getSelect()->group('countrycode');
$countries = array();
foreach($collection as $item)
$countries[$item->getcountrycode()] = Mage::getModel('directory/country')->load($item->getcountrycode())->getName();
return $countries;
}