var pop = document.getElementById('popup');

var xoffset = 15;
var yoffset = 10;

document.onmousemove = function(e) {
  var x, y, right, bottom;
  
  try { x = e.pageX; y = e.pageY; } // FF
  catch(e) { x = event.x; y = event.y; } // IE

  right = (document.documentElement.clientWidth || document.body.clientWidth || document.body.scrollWidth);
  bottom = (window.scrollY || document.documentElement.scrollTop || document.body.scrollTop) + (window.innerHeight || document.documentElement.clientHeight || document.body.clientHeight || document.body.scrollHeight);

  x += xoffset;
  y += yoffset;

  if(x > right-pop.offsetWidth)
	x = right-pop.offsetWidth;
 
  if(y > bottom-pop.offsetHeight)
	y = bottom-pop.offsetHeight;
  
  pop.style.top = y+'px';
  pop.style.left = x+'px';
}

function hoverin(text) {
  pop.innerHTML = text;
  pop.style.display = 'block';
}

function hoverout() {
  pop.style.display = 'none';
}