handle keyboard shortcuts ending with '-'

IPython/html/static/base/js/keyboard.js

@@ -88,12 +88,14 b' IPython.keyboard = (function (IPython) {'
         // 3. Sort '-' separated modifiers into the order alt-ctrl-meta-shift
         // 4. Normalize keys
         shortcut = shortcut.toLowerCase().replace('cmd', 'meta');
+        shortcut = shortcut.replace('--', '-');  // catch shortcuts using '-' key
         var values = shortcut.split("-");
         if (values.length === 1) {
             return normalize_key(values[0]);
         } else {
             var modifiers = values.slice(0,-1);
             var key = normalize_key(values[values.length-1]);
+            key = key || '-'; // '-' will make the key undefined, since we split on it
             modifiers.sort();
             return modifiers.join('-') + '-' + key;
         }

IPython/html/static/notebook/js/quickhelp.js

@@ -71,8 +71,9 b' var IPython = (function (IPython) {'
         return build_div('<h4>Command Mode (press <code>Esc</code> to enable)</h4>', command_shortcuts);
     };
 
-    var special_case = { pageup: "PageUp", pagedown: "Page Down" };
+    var special_case = { pageup: "PageUp", pagedown: "Page Down", '': '-' };
     var prettify = function (s) {
+        s = s.replace('--', '-'); // catch shortcuts using '-' key
         var keys = s.split('-');
         var k, i;
         for (i in keys) {