Passes through unused key events.

unpacked/extensions/MathMenu.js

@@ -193,8 +193,13 @@
       },
       ".MathJax_MenuClose:hover span": {
         "background-color":"#CCC!important"
+      },
+      ".MathJax:focus": {
+        display:"inline-block",
+        outline:"none",
+        border:"1px dotted",
+        margin:"-1px"
       }
-
     }
   });
 
@@ -236,6 +241,7 @@
         this.Space(event, menu);
         break;
       default:
+        return;
         break;
       }
       return FALSE(event);