var currentPanel;
   
   function showPanel(panelNum) {
      //hide visible panel, show selected panel, 
      //set tab
      if (currentPanel != null) {
         hidePanel();
      }
      document.getElementById 
         ('panel'+panelNum).style.visibility = 'visible';
         currentPanel = panelNum;
         setState(panelNum);
   }
   
   function hidePanel() {
      //hide visible panel, unhilite tab
      document.getElementById('panel'+currentPanel).style.visibility = 'hidden';
      document.getElementById('tab'+currentPanel).style.backgroundColor = '#ffffff';
      document.getElementById('tab'+currentPanel).style.color = '#6395AE';
      document.getElementById('tab'+currentPanel).style.borderColor = '#99CCFF';
   }
   
   function setState(tabNum) {
      if (tabNum==currentPanel) {
         document.getElementById('tab'+tabNum).style.backgroundColor = '#E3F3FC';
         document.getElementById('tab'+tabNum).style.color = '#354E79';
         document.getElementById('tab'+tabNum).style.borderColor = '#99CCFF';
      }
      else {
         document.getElementById('tab'+tabNum).style.backgroundColor = '#ffffff';
         document.getElementById('tab'+tabNum).style.color = '#6395AE';
         document.getElementById('tab'+tabNum).style.borderColor = '#99CCFF';
      }
   }
   
   function hover(tab) {
         tab.style.backgroundColor = '#184796';
         tab.style.color = '#fff';
         tab.style.borderColor = '#184796';
   }