function okno(url,w,h,params) {
       var windowW=w;
       var windowH=h;
       var windowX = (screen.width/2)-(windowW/2);
       var windowY = (screen.height/2)-(windowH/2)-50;
       var page = url;
       windowprops = "height="+windowH+",width="+windowW+",left="+windowX+",top="+windowY+",screenX="+windowX+",screenY="+windowY;
       if (params!="") windowprops += params;
       window.open(page, "_blank", windowprops);
   }

   function checkauthor(theForm, theFieldName) {
       var theField = theForm.elements[theFieldName];
       var msg = "Prosím zadaj meno.";
       var val = theField.value;
       
       if (val=='') {
           theField.select();
           alert(msg);
           theField.focus();
           return false;
       }
       else {
           theField.value = val;
           }
       return true;
   }

   function ays() {
	   return confirm("Naozaj ?");
   }