m1 = new Image();
m1.src = "images/bt_news_off.gif";
m1_on = new Image();
m1_on.src = "images/bt_news_on.gif";

m2 = new Image();
m2.src = "images/bt_produkty_off.gif";
m2_on = new Image();
m2_on.src = "images/bt_produkty_on.gif";

m3 = new Image();
m3.src = "images/bt_praca_off.gif";
m3_on = new Image();
m3_on.src = "images/bt_praca_on.gif";

m4 = new Image();
m4.src = "images/bt_firma_off.gif";
m4_on = new Image();
m4_on.src = "images/bt_firma_on.gif";

m5 = new Image();
m5.src = "images/bt_kontakt_off.gif";
m5_on = new Image();
m5_on.src = "images/bt_kontakt_on.gif";

m6 = new Image();
m6.src = "images/bt_wiecej_off.gif";
m6_on = new Image();
m6_on.src = "images/bt_wiecej_on.gif";

function img_over(obrazek) {
var img=document[obrazek];
if(img)
{
img.src = eval(obrazek + "_on.src");
}
} 

function img_out(obrazek) {
var img=document[obrazek];
if(img)
{
	img.src = eval(obrazek + ".src");
}
} 

//Preload buttonów podmiany
function preload() {
  if (!document.images) return;
  var ar = new Array();
  var arguments = preload.arguments;
  for (var i = 0; i < arguments.length; i++) {
    ar[i] = new Image();
    ar[i].src = arguments[i];
  }
}

function showCase()
{
window.open('case_study.html','casestudy', 'height=320,width=390,menubar=0,status=0,titlebar=0,toolbar=0');
}