function Fenetre_image_ouvre(posX,posY,tailleX,tailleY){
  var fenetre=document.createElement("div");

  fenetre.className="div_fenetre_image";
  fenetre.style.left=posX+'px';
  fenetre.style.top=posY+'px';
  fenetre.style.width=tailleX+'px';
  fenetre.style.height=tailleY+'px';

  document.body.appendChild(fenetre);

  var xhr=getXhr();

  xhr.onreadystatechange=function(){
    if(xhr.readyState==4 && xhr.status==200){
      image=xhr.responseText;
      // ajoute les options à la liste
      fenetre.innerHTML=image;
    }
  }

  xhr.open("POST","xhr_fenetre.php",true);
  xhr.setRequestHeader('Content-Type','application/x-www-form-urlencoded');

  xhr.send("ai="+1+"ii="+1);
}