// **funzione per la finestra popup centrata rispetto allo schermo
function openCenteredWindow(thepage,thewname,wheigth,wweigth,scroll_,menu_,tool_,resize_){
   var aw = screen.availWidth;
   var ah = screen.availHeight;
   var film_width = wweigth;
   var film_heigth = wheigth;

   posW = (screen.availWidth/2)-(film_width/2);
   posH = (screen.availHeight/2)-(film_heigth/2);

   if(document.all)
     newWin = window.open(thepage,thewname,"toolbar="+tool_+",scrollbars="+scroll_+",menubar="+menu_+",resizable="+resize_+",height="+film_heigth+",width="+film_width+",left="+posW+",top="+posH);
   else
     newWin = window.open(thepage,thewname,"toolbar="+tool_+",scrollbars="+scroll_+",menubar="+menu_+",resizable="+resize_+",height="+film_heigth+",width="+film_width+",screenX="+posW+",screenY="+posH);
   newWin.focus();
}