var NS4 = (document.layers) ? 1 : 0; // is it NS4?
var IE4 = (document.all) ? 1 : 0;    // is it IE4?
var ver4 = (NS4 || IE4) ? 1 : 0;     // is it NS4 or IE4 at all?

// tunes up browser-depended variables
if (NS4)
{
 doc = 'document';
 sty = '';
}
else
{
 doc = 'document.all';
 sty = '.style';
}


 var currentMenu = null;

 function switchMenu(menu)
 {
  if (menu == '')
   return false;

  var menuObj = document.getElementById(menu);

  if (menuObj != null)
  {
   if (currentMenu != null && currentMenu != menuObj)
   {
    currentMenu.style.visibility = 'hidden';
    currentMenu.style.display = 'none';
   }

   menuObj.style.visibility = ((menuObj.style.visibility == 'hidden') ? 'visible' : 'hidden');
   menuObj.style.display = ((menuObj.style.display == 'none') ? 'inline' : 'none');

   currentMenu = menuObj;

   return true;
  }

  return false;
 }

function MM_swapImgRestore()
{ //v3.0
 var i, x, a = document.MM_sr;

 for (i = 0; a && i < a.length && (x = a[i]) && x.oSrc; i++)
  x.src=x.oSrc;
}
function MM_preloadImages()
{ //v3.0
 var d = document;

 if (d.images)
 {
  if (!d.MM_p)
   d.MM_p = new Array();

  var i, j = d.MM_p.length, a = MM_preloadImages.arguments;

  for (i = 0; i < a.length; i++)
   if (a[i].indexOf("#") != 0)
   {
    d.MM_p[j] = new Image;
    d.MM_p[j++].src = a[i];
   }
 }
}

function MM_findObj(n, d) { //v4.01
  var p,i,x;  if(!d) d=document; if((p=n.indexOf("?"))>0&&parent.frames.length) {
    d=parent.frames[n.substring(p+1)].document; n=n.substring(0,p);}
  if(!(x=d[n])&&d.all) x=d.all[n]; for (i=0;!x&&i<d.forms.length;i++) x=d.forms[i][n];
  for(i=0;!x&&d.layers&&i<d.layers.length;i++) x=MM_findObj(n,d.layers[i].document);
  if(!x && d.getElementById) x=d.getElementById(n); return x;
}

function MM_swapImage() { //v3.0
  var i,j=0,x,a=MM_swapImage.arguments; document.MM_sr=new Array; for(i=0;i<(a.length-2);i+=3)
   if ((x=MM_findObj(a[i]))!=null){document.MM_sr[j++]=x; if(!x.oSrc) x.oSrc=x.src; x.src=a[i+2];}
}

 function checkFeedBack(form)
 {
  if ((form.e_mail.value == '')  ||
   (form.e_mail.value.indexOf('@') < 1) || (form.e_mail.value.indexOf('.') < 4))
  {
   alert('Пожалуйста, укажите правильный e-mail адрес.');
   form.e_mail.focus();
   return false;
  }

  if (form.question.value == '')
  {
   alert('Пожалуйста, укажите текст сообщения.');
   form.question.focus();
   return false;
  }

  return true;
 }