Selection Box On Flags?

Hey,

If I use this Plugin I get some Selection Box On Flags on the Flags.
I tried your plugin some time ago and did’t find thes boxes on the flags. How can I remove the boxes? Or what is the reason for these boxes?

Here is a screenshot of that problem
https://s1.directupload.net/images/140726/mm79tl9l.png

https://www.ads-software.com/plugins/language-bar-flags/