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Element.implement({

  grow: function(amount){
    var tween = this.get('tween');
    var to = this.getSize().y + amount.toInt();
    tween.start('height', to);
    return this;
  }

});

window.addEvent('domready', function(){
    
    $('comments').addEvents({
        focus: function(){
            this.grow(50);
        },
        blur: function(){
            // this.shrink();
            this.value = "hey make me shrink here or else I'll just keep growing ...";
        }
    });
    
});