function addLoadEvent(func) {
  var oldonload = window.onload;
  if (typeof window.onload != 'function') {
    window.onload = func;
  } else {
    window.onload = function() {
      oldonload();
      func();
    }
  }
}

function addClass(elem, value) {
  if (!elem.className) {
    elem.className = value;
  } else {
    elem.className+= " ";
    elem.className+= value;
  }
}

function removeClass(elem, value) {
	elem.className = elem.className.replace(value,"").replace(/^\s+|\s+$/,"");
}

function showHide(elem) {
	elem = document.getElementById(elem);
	disp = (elem.style.display == 'none') ? 'block' : 'none';
	elem.style.display = disp;
}