var shown = "";

function showBlock(id)
{
  if (shown != "")
  {
    document.getElementById(shown).style.display = "none";
    document.getElementById(shown + "-item").style.textDecoration = "none";
  }

  shown = id;
  document.getElementById(id).style.display = "block";
  document.getElementById(id + "-item").style.textDecoration = "underline";
}