var sStep = 16;  
 var sTimeout = 15;  
 var sLeft = 160;  
 var sRight = 160;  
 var wObj;  

 function winOpen() {  
  wObj.style.display = 'block';  
   
  if (sLeft > 0) {  
  sRight += sStep;  
  sLeft -= sStep;  
  var rect = 'rect(auto, '+ sRight +'px, auto, '+ sLeft +'px)';  
  wObj.style.clip = rect;  
  setTimeout(winOpen, sTimeout);  
  }  
 }  

 function winClose() {  
  if (sLeft < sRight) {  
  sRight -= sStep;  
  sLeft += sStep;  
  var rect = 'rect(auto, '+ sRight +'px, auto, '+ sLeft +'px)';  
  wObj.style.clip = rect;  
  setTimeout(winClose, sTimeout);  
  }  
  else wObj.style.display = 'none';  
  }