I tried to use this plugin on 3.5.1 but I didn´t get it working, but I found a solution. May be it is a little bit a "gipsy" way, but it works for me.
Bevor I tested different things but didn´t get it running. By luck my developer was in our office today and he gave me the right hint.
By default the jQuery v1.8.3 is integrated on WordPress 3.5.1 but the FixText-Plugin seems not to work with it. So we switched to jQuery v1.7.2.
Therefore I went to wp-include/js/jquery and commented out the file "jquery.js". Then I created a new "jquery.js"-file with the content of jQuery v1.7.2 (http://code.jquery.com/jquery-1.7.2.js).
With this change it is working now.
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