Element.implement({ 
    clearDefault: function(){ 
		var defaultValue = this.get('value');
        this.addEvents({ 
            'focus': function(){ 
                if( this.get('value') == defaultValue ) this.set('value',''); 
            }, 
            'blur': function(){ 
                if( this.get('value') == "" ) this.set('value',defaultValue); 
            } 
        }); 
    } 
}); 

window.addEvent('domready', function() {
	$$('.cleardefault').clearDefault();
});