function open_window(src, width, height){
   if(width==0)   width=500;
   if(height==0)  height=400;
   var left = (screen.availWidth/2) - (width/2);
   var top = (screen.availHeight/2) - (height/2);
   info=window.open(src,'photo','resizable=1, scrollbars=1, toolbar=0, status=0, width='+width+', height='+height+', left='+left+', top='+top);
   info.focus();
 }