function ShowPic ( img ){
  var elem = document.getElementById(img);
  var elemstyle = elem.style;
  var width  = document.body.clientWidth;
  var height = document.body.clientHeight;
  var color  = document.body.bgColor;
  elemstyle.backgroundColor = 'white';
  elemstyle.left = width/2 - elem.offsetWidth / 2;
  elemstyle.top  = height/2 - elem.offsetHeight / 2;
  elemstyle.visibility="visible";
}

function HidePic ( img ){
  var elem = document.getElementById(img);
  var elemstyle = elem.style;
  if ( parseInt( elemstyle.left ) - event.clientX < 0  && 
       parseInt( elemstyle.left ) + elem.offsetWidth - event.clientX > 0  && 
       parseInt( elemstyle.top ) + elem.offsetHeight - event.clientY > 0  && 
       parseInt( elemstyle.top ) - event.clientY < 0 
  ){ 
  } else {
    elemstyle.visibility="hidden";
  }
}

function HidePic2 ( img ){
  document.getElementById(img).style.visibility="hidden";
}