$dir){ if(!file_exists(__DIR__ . "/skins/".$dir."/0.png") ){ unset($skinsDir[$key]); } } ?>

In the directory wp-content/plugins/wp-404-page/skins where different plugin`s skins are.
If you want to create your style, then you need::
0. Examples can be seen in the same directory.
1. In the directory wp-content/plugins/wp-404-page/skins to create a folder with any name;
2. Add the created image folder with 100x100 resolution and with titles: "0.png", "1.png", "ask.png", "none.png";
3. Activate skin on this page.','wp-404tboc-page'); ?>

"; } else{ echo ""; } } ?>
$dir ". __("Active",'wp-404tboc-page')."
$dir