message: Remove the gray background when the menu is open
  Based on feedback from multiple people.
diff: (function() {
  var currentMenu;
  var backdrop = document.createElement("div");
  - backdrop.style = "display:none;position:fixed;width:100%;height:100%;z-index:1;background:rgba(50, 50, 50, 0.5)";
  + backdrop.style = "display:none;position:fixed;width:100%;height:100%;z-index:1";
  document.documentElement.insertBefore(backdrop, document.querySelector("body"));
  function previous(allItems, item) {
  var i = 1;
  // it is not the same as GitHub, but GitHub allows you to tab yourself out
  // of the menu without closing it (which is horrible behavior)
  switchTo = e.shiftKey ? last(allItems) : allItems[0];
  - } else if (e.shiftKey && currentItem === allItems[0]) {
  + } else if (e.shiftKey && currentLink === allItems[0]) {
  // if you tab your way out of the menu, close it
  // this is neither what GitHub nor the WAI example do,
  // but is a rationalization of GitHub's behavior: we don't want users who know how to
  