nearly everything working with activedescendant... then decide it's wrong.

less/dropdowns.less

@@ -34,11 +34,16 @@
   margin-top: 8px;
   margin-left: 2px;
 }
-.dropdown:hover .caret,
+.dropdown a:focus .caret,
+.dropdown a:hover .caret,
 .open .caret {
   .opacity(100);
 }
 
+.navbar .nav .open > a {
+  color: @navbarLinkColorActive;
+}
+
 // The dropdown menu (ul)
 // ----------------------
 .dropdown-menu {
@@ -90,11 +95,17 @@
 // -----------
 .dropdown-menu li > a:hover,
 .dropdown-menu .active > a,
-.dropdown-menu .active > a:hover {
+.dropdown-menu .active > a:hover,
+.dropdown-menu:hover #aria-active > a:hover,
+.dropdown-menu #aria-active > a {
   color: @dropdownLinkColorHover;
   text-decoration: none;
   background-color: @dropdownLinkBackgroundHover;
 }
+.dropdown-menu:hover #aria-active > a {
+  color: @dropdownLinkColor;
+  background-color: @dropdownBackground;
+}
 
 // Open state for the dropdown
 // ---------------------------

less/navbar.less

@@ -228,6 +228,7 @@
   padding: ((@navbarHeight - @elementHeight) / 2 - 1) 5px ((@navbarHeight - @elementHeight) / 2);
 }
 // Hover
+.navbar .nav > li > a:focus,
 .navbar .nav > li > a:hover {
   background-color: @navbarLinkBackgroundHover; // "transparent" is default to differentiate :hover from .active
   color: @navbarLinkColorHover;
@@ -236,7 +237,8 @@
 
 // Active nav items
 .navbar .nav .active > a,
-.navbar .nav .active > a:hover {
+.navbar .nav .active > a:hover,
+.navbar .nav .active > a:focus {
   color: @navbarLinkColorActive;
   text-decoration: none;
   background-color: @navbarLinkBackgroundActive;
@@ -343,6 +345,7 @@
 }
 
 // Dropdown link on hover
+.navbar .nav li.dropdown.active > .dropdown-toggle:focus,
 .navbar .nav li.dropdown.active > .dropdown-toggle:hover {
   color: @white;
 }