I match the wanted tags by using following syntax...
function wfRenderArticleSectionCheck($input, $args, &$parser) { global $wgTitle, $wgArticle, $wgParser, $wgLang, $wgLanguageCode;
$lan = $wgLang->getCode(); if($args[lan] == $lan) { return $input; } else { return ''; }
}
The empty space is conform with the entire space the non-matched content would take up...
So you have tags around all the content saying what language it's in, and only the correct language should be displayed?
I can't see why there would be blank space, your code looks correct to me. Do you have a demo website where I can see it running?