document.observe("dom:loaded", function() { 
var offtopics = $$('.button_offtopic');
offtopics.each(function(block) {
block.observe('click', function() {
var element=this.parentNode.getElementsByTagName('span')[0];if(element.style.display=='none'){element.style.display='';this.setValue('Fechar Offtopic');}else{element.style.display='none';this.setValue('Offtopic');}
});
});
});