var timerId = 0;

function buttonOn(button) {
  if (!button.getAttribute('src_inactive')) {
    button.setAttribute('src_inactive',button.src);
  }
  if (button.src.indexOf('?') > -1) button.src = button.src+'&hover=1';
  else button.src = button.src+'?hover=1';
}

function buttonOff(button) {
  if (button.getAttribute('src_inactive')) {
    button.src = button.getAttribute('src_inactive');
  }
}

function hideAllNow() {
  clearTimer();

  var buttons = document.getElementById('buttons');
  for (var i=0; i<buttons.childNodes.length; i++)
    if (buttons.childNodes[i].className == 'button') {
      var b = buttons.childNodes[i];
      buttonOff(b);
      document.getElementById(b.id+'_overlay').style.visibility='hidden';  
    }
}

function hideAllDelayed() {
  timerId = setTimeout(hideAllNow,200);
}

function showOverlay(button) {
  clearTimer();

  var buttons = document.getElementById('buttons');
  for (var i=0; i<buttons.childNodes.length; i++)
    if (buttons.childNodes[i].className == 'button') {
      var b = buttons.childNodes[i];
      if (b.id == button.id) {
        buttonOn(b);
        document.getElementById(b.id+'_overlay').style.visibility='visible';  
      } else {
        buttonOff(b);
        document.getElementById(b.id+'_overlay').style.visibility='hidden';  
      }
    }
}

function clearTimer() {
  if (timerId) {
    clearTimeout(timerId);
    timerId = 0;
  }
}

function showCredits() {
  document.getElementById('credits').style.visibility='visible';
}
function hideCredits() {
  document.getElementById('credits').style.visibility='hidden';
}

function enableIEAlpha(ob) {
}