var opened=false;

    window.onload = function() {
        resizeDivHeight = new fx.Height('navigation',{duration:600});
    };

    function toggleopen(){
        if(opened==false){
            resizeDivHeight.custom(0,100);//First Number is starting height, Second is ending height.
            opened=true;
        }else{
            resizeDivHeight.custom(100,0);//First Number is starting height, Second is ending height.
            opened=false;
        }
    }