function hideMenus() {
 document.getElementById("navButton1").style.backgroundImage = "url(images/nav_button-left.gif)";
 document.getElementById("menu2").style.display = "none";
 document.getElementById("navButton2").style.backgroundImage = "url(images/nav_button-center.gif)";
 document.getElementById("navButton3").style.backgroundImage = "url(images/nav_button-center.gif)";
 document.getElementById("menu4").style.display = "none";
 document.getElementById("navButton4").style.backgroundImage = "url(images/nav_button-center.gif)";
 document.getElementById("menu5").style.display = "none";
 document.getElementById("navButton5").style.backgroundImage = "url(images/nav_button-right.gif)";
}

function showMenu(m) {
 hideMenus();
 if (m == 1) {
  document.getElementById("navButton1").style.backgroundImage = "url(images/nav_selected-left.gif)";
 }
 else {
  if (m == 2) {
  document.getElementById("navButton2").style.backgroundImage = 'url(images/nav_selected-center.gif)';
  document.getElementById("menu2").style.display = "block";
  }
  else {
   if (m == 3) {
    document.getElementById("navButton3").style.backgroundImage = 'url(images/nav_selected-center.gif)';
   }
   else {
    if (m == 4) {
     document.getElementById("navButton4").style.backgroundImage = 'url(images/nav_selected-center.gif)';
     document.getElementById("menu4").style.display = "block";
    }
    else {
     if (m == 5) {
      document.getElementById("navButton5").style.backgroundImage = 'url(images/nav_selected-right.gif)';
      document.getElementById("menu5").style.display = "block";
     }
    }
   }
  }
 }
}