var usedTab;
var newTab;
var usedBlock;
var newBlock;
function ActivateTab(tabName)
{    
    usedTab = document.getElementById('usedTab');
    newTab = document.getElementById('newTab');
    usedBlock = document.getElementById('usedBlock');
    newBlock = document.getElementById('newBlock');

    switch(tabName)
    {
         case 'new':
            usedTab.className = 'inactive';
            usedBlock.className = 'inactive';
            newTab.className = 'active';
            newBlock.className = 'active';
            nCurrent = 'new';
          break;
        case 'used':       
            usedTab.className = 'active';
            usedBlock.className = 'active';
            newTab.className = 'inactive';
            newBlock.className = 'inactive';
            nCurrent = 'used';
          break;      
        default:       
            usedTab.className = 'active';
            usedBlock.className = 'active';
            newTab.className = 'inactive';
            newBlock.className = 'inactive';
            nCurrent = 'used';
          break;
    }    
}