var selectedTab = 0;

function tabclick(n) {
  if (n === selectedTab) return; // nothing to do.
  var li = document.getElementById('tab' + selectedTab);
  li.className = 'curvyRedraw';
  //curvyCorners.adjust(li, 'className', 'curvyRedraw'); // Remove the 'select' style
  li = document.getElementById('page' + selectedTab);
  li.style.display = 'none';                // hide the currently selected sub-page
  li = document.getElementById('page' + n);
  li.style.display = 'block';               // show the new sub-page
  li = document.getElementById('tab' + n);  // get the new (clicked) tab
  li.className = 'curvyRedraw select';
  //curvyCorners.adjust(li, 'className', 'curvyRedraw select'); // and update its style
  curvyCorners.redraw();        // Redraw all elements with className curvyRedraw
  selectedTab = n;              // store for future reference
}