function randomNumber(limit){
  return Math.floor(Math.random()*limit);
}
function randomImage()
{
  var r;
  // CHANGE NUMBER IN BRACKETS TO CHANGE NUMBER OF EXISTING
  // GRAPHIC FILES "pic_top.jpg"
  r = randomNumber(18)+1;

  document.write('<img src="img/pic_top'+r+'.jpg" width="750" height="130">');
}

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];}
}

// SHOW OBJECT

function show(szDivID) {
  if (document.layers) { // NN4+
      document.layers[szDivID].visibility = "show";
      document.layers[szDivID].display = "block";
	 }
 else if (document.getElementById) { // gecko(NN6) + IE 5+
    var obj = document.getElementById(szDivID);
    var objSD = document.getElementById(szDivID+"SD");

      obj.style.visibility = "visible";
      obj.style.display = "block";
    } 
   else if (document.all) { // IE 4
      document.all[szDivID].style.visibility = "visible";
      document.all[szDivID].style.display = "block";
  }
}

// HIDE OBJECT

function hide(szDivID) {
  if (document.layers) { // NN4+
    if (document.layers[szDivID].visibility == 'visible') {
      document.layers[szDivID].visibility = "hide";
      document.layers[szDivID].display = "none"; 
    } 
  } else if (document.getElementById) { // gecko(NN6) + IE 5+
    var obj = document.getElementById(szDivID);
    var objSD = document.getElementById(szDivID+"SD");

    if (obj.style.visibility == 'visible') {
      obj.style.visibility = "hidden";
      obj.style.display = "none";
    } 
  } else if (document.all) { // IE 4
    if (document.all[szDivID].style.visibility == 'visible') {
      document.all[szDivID].style.visibility = "hidden";
      document.all[szDivID].style.display = "none";
    } 
  }
}

// HIDE ALL OBJECTS
function hideAll(which) {
	if (which == "sub_kursy") {
		hide('sub_tlumaczenia');hide('sub_kultura');hide('sub_dele');hide('sub_kontakt');
	}
	if (which == "sub_tlumaczenia") {
		hide('sub_kursy');hide('sub_kultura');hide('sub_dele');hide('sub_kontakt');
	}
	if (which == "sub_kultura") {
		hide('sub_tlumaczenia');hide('sub_kursy');hide('sub_dele');hide('sub_kontakt');
	}
	if (which == "sub_dele") {
		hide('sub_tlumaczenia');hide('sub_kultura');hide('sub_kursy');hide('sub_kontakt');
	}
	if (which == "sub_kontakt") {
		hide('sub_tlumaczenia');hide('sub_kultura');hide('sub_dele');hide('sub_kursy');
	}
}

// TOGGLE SHOW/HIDE OBJECT

function toggle(szDivID) {
  
  if (document.layers) { // NN4+
    if (document.layers[szDivID].visibility == 'visible') {
      document.layers[szDivID].visibility = "hide";
      document.layers[szDivID].display = "none";
    } else {
      document.layers[szDivID].visibility = "show";
      document.layers[szDivID].display = "block";
    }
  } else if (document.getElementById) { // gecko(NN6) + IE 5+
    var obj = document.getElementById(szDivID);

    if (obj.style.visibility == 'visible') {
		
	  obj.style.visibility = "hidden";
      obj.style.display = "none";
	  
    } else {
	  
	  obj.style.visibility = "visible";
      obj.style.display = "block";

    }
  } else if (document.all) { // IE 4
    if (document.all[szDivID].style.visibility == 'visible') {
      document.all[szDivID].style.visibility = "hidden";
      document.all[szDivID].style.display = "none";
    } else {
      document.all[szDivID].style.visibility = "visible";
      document.all[szDivID].style.display = "block";
    }
  }
}