//<a href="chemin/du/fichier.html" onclick="return open_popup('this','_blank','500','400','')">
//ouvre une popup centerer par default
function open_popup(lien,fenetre,width,height,param){
	var left=(screen.availWidth-width)/2;
	var top=(screen.availHeight-height)/2;
	if (top <0) top=0;
	if (param!='') param=','+param;
	window.open(lien,fenetre,'top='+top+',left='+left+',width='+width+',height='+height+',scrollbars=yes'+param);
	return false;
}