function scrollDown(elem){
  if(typeof elem == 'string')
    seatmapDiv = document.getElementById(elem);
  if(seatmapDiv)
    seatmapDiv.scrolling = setTimeout(function(){seatmapDiv.scrollTop+=20;}, 100);
}

function scrollUp(elem){
  if(typeof elem == 'string')
    seatmapDiv = document.getElementById(elem);
  if(seatmapDiv)
    seatmapDiv.scrolling = setTimeout(function(){seatmapDiv.scrollTop-=20;}, 100);
}

function displayIPhoneControls() { 
    var objRegExp  = /^.*\([iPod|iPhone].*\).*Mobile.*Safari.*$/i;
    if (objRegExp.test(navigator.userAgent)==true) {
      document.getElementById('scroll_buttons').style.display = 'block';
    }
}