function getMouseY(event)
{
 var e = event || window.event;
 return e.clientY;
}

 var popenabled = 0;

document.onmousemove = function(event){

 mouseY = getMouseY(event);
 if(mouseY<20)
 {
  if (popenabled > 0) {
   
   }else{
    popenabled = 1;
    popup();
   }
  
 }
};