var currentPanel;
			
function showPanel(panelNum) {
  //hide visible panel, show selected panel, 
  //set tab
  if (currentPanel != null) {
	 hidePanel();
  }
  document.getElementById 
	 ('panel'+panelNum).style.visibility = 'visible';
  document.getElementById 
	 ('panel'+panelNum).style.display = 'block';
	 currentPanel = panelNum;
	 setState(panelNum);
}

function hidePanel() {
  //hide visible panel, unhilite tab
  document.getElementById
	('panel'+currentPanel).style.visibility = 
	 'hidden';
  document.getElementById
	('panel'+currentPanel).style.display = 
	 'none';
  document.getElementById
	('tab'+currentPanel).style.backgroundColor = 
	'#ffffff';
  document.getElementById
	('tab'+currentPanel).style.color = 'navy';
}

function setState(tabNum) {
  if (tabNum==currentPanel) {
	 document.getElementById 
	   ('tab'+tabNum).style.backgroundColor = 
	   '#ddddff';
	 document.getElementById
	   ('tab'+tabNum).style.color = 'red';
  }
  else {
	 document.getElementById
	   ('tab'+tabNum).style.backgroundColor = 
	   '#ffffff';
	 document.getElementById
	   ('tab'+tabNum).style.color = 'navy';
  }
}

function hover(tab) {
  tab.style.backgroundColor = 'ddddff';
}