Gets overview form header.
array Header array definition as expected by theme_tablesort().
public function overviewFormHeader() {
$languages = array();
foreach ($this
->getLanguages() as $langcode => $language) {
$languages['langcode-' . $langcode] = array(
'data' => $language
->getName(),
);
}
$header = array(
'source' => array(
'data' => t('Source text'),
),
'context' => array(
'data' => t('Context'),
),
) + $languages;
return $header;
}