function showDropDown(dropDownId) {
  clearInterval(document.getElementById(dropDownId).dropDownTimer);
  document.getElementById(dropDownId).style.display = 'block';
}

function hideDropDown(dropDownId) {
  document.getElementById(dropDownId).dropDownTimer = setInterval('doHideDropDown(\''+dropDownId+'\');', 300);
}

function doHideDropDown(dropDownId) {
  clearInterval(document.getElementById(dropDownId).dropDownTimer);
  document.getElementById(dropDownId).style.display = 'none';
}