if (document.images) {
  //menu
  var homeOFF = new Image(); homeOFF.src="images/btns/btn_home.jpg";
  var homeON = new Image(); homeON.src="images/btns/btn_home_roll.jpg";
  var projOFF = new Image(); projOFF.src="images/btns/btn_proj.jpg";
  var projON = new Image(); projON.src="images/btns/btn_proj_roll.jpg";

  var leedOFF = new Image(); leedOFF.src="images/btns/btn_leed.jpg";
  var leedON = new Image(); leedON.src="images/btns/btn_leed_roll.jpg";
  var subcOFF = new Image(); subcOFF.src="images/btns/btn_sub.jpg";
  var subcON = new Image(); subcON.src="images/btns/btn_sub_roll.jpg";

  var aboutOFF = new Image(); aboutOFF.src="images/btns/btn_about.jpg";
  var aboutON = new Image(); aboutON.src="images/btns/btn_about_roll.jpg";
  var contactOFF = new Image(); contactOFF.src="images/btns/btn_contact.jpg";
  var contactON = new Image(); contactON.src="images/btns/btn_contact_roll.jpg";
}


function act(imgName) {
 if (document.images) 
  document[imgName].src = eval(imgName + 'ON.src')
}

function inact(imgName) {
 if (document.images)
  document[imgName].src = eval(imgName + 'OFF.src')
}