Carsten,

Are you sure the html formatting will encode single-quote ? it was not the case in the past, but I may have missed something.

Anyway you're right, the best option is to replace 
<option value='<?php $clang->eT("Open","js") ?>'><?php $clang->eT("Open") ?></option>
by
<option><?php $clang->eT("Open") ?></option>

I will update the patch