var myrules = {
        'img.img_rollover' : function(element)
        {	
            
                // preload the rollover image
                preload(element);

                // onmouse over handler
                element.onmouseover = function()
                {
                        rollover(this);		
                }

                // onmouse out handler
                element.onmouseout = function()
                {
                        rollover(this);
                }			

        }
};


Behaviour.register(myrules);