js: Add keyboard navigation for menus

Once the input focus is in the menu system (for instance by Shift+Tab
from the puzzle), you can move left and right through the menu bar and
up and down within each menu.  Enter selects a menu item.  The current
menu item is tracked by giving it the input focus.

1 files changed, 1 insertions, 0 deletions

diff --git a/emcclib.js b/emcclib.js
index 47963bb..5c1d039 100644
--- a/emcclib.js
+++ b/emcclib.js
@@ -111,6 +111,7 @@ mergeInto(LibraryManager.library, {
         var tick = document.createElement("span");
         tick.className = "tick";
         label.appendChild(tick);
+        label.tabIndex = 0;
         label.appendChild(document.createTextNode(" " + name));
         item.appendChild(label);
         var submenu = document.createElement("ul");