function toggle_visible(obj) {

	obj = document.getElementById(obj);
	if (obj.style.visibility == 'visible'){
		obj.style.visibility = 'hidden';
		obj.style.top = -300;
	} else {
		obj.style.visibility = 'visible';
		obj.style.top = 150;
	} // end if...then

	return true;

} // end function toggle_visible