I'm afraid I'm not sure whether this is a MW bug or a Firefox bug...
While testing the following page:
https://pt.wiktionary.org/wiki/Especial:Filtro_de_abusos/examine/log/1542
I noticed that none of the three buttons are working in Firefox 16.0.1.
Nevertheless, it seems to work fine in IE8.
Despite intrinsic browser differences, buttons should work cross-browser.
Version: master
Severity: normal