$wgTranslateCC['wiki-sidebar'] = 'addSidebarMessageGroup';
function addSidebarMessageGroup( $id ) {

$mg = new WikiMessageGroup( $id, 'sidebar-messages' );
$mg->setLabel( 'Sidebar' );
$mg->setDescription( 'Messages used in the sidebar of this wiki' );
return $mg;

}

According to https://www.mediawiki.org/wiki/Help:Extension:Translate/Unstructured_element_translation the preceding code should be added to config file. Please do so for Wikimania 2013, thanks.

Version: unspecified
Severity: enhancement