var sCurrentTab = '';

function selectTab( sTab ) {
  if( sCurrentTab == sTab ) { return; }

  var oTab = document.getElementById( sCurrentTab );  
  if( oTab != null ) {
    oTab.style.display = 'none';
  }
  
  var oTab = document.getElementById( sTab );  
  if( oTab != null ) {
    oTab.style.display = 'block';
  }
  sCurrentTab = sTab;
}