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

function addResizeEvent(func) {
  var oldonresize = window.onresize;
  if (typeof window.onresize != 'function') {
    window.onresize = func;
  } else {
    window.onresize = function() {
      oldonresize();
      func();
    }
  }
}

function popup(url, windowname, width, height) {
	var url = url;
	var windowname = windowname;
	var width = width;
	var height = height;
	var left = (screen.width - width) / 2;
	var top = (screen.height - height) / 2;
	var params = 'width=' + width + ', height=' + height;
		params += ', top=' + top + ', left=' + left;
		params += ', directories=no';
		params += ', location=no';
		params += ', menubar=no';
		params += ', resizable=no';
		params += ', scrollbars=no';
		params += ', status=no';
		params += ', toolbar=no';

	var newwin = window.open(url, 'Popup', '"' + params + '"');

	if (window.focus) {
		newwin.focus()
	}
	return false;
}