code: function(e) {
              var c = Event.getCharCode(e);
  
              //alert(Event.getCharCode(e) + ", " + e.keyCode + ", " + e.charCode);
  
              // special keys
              if (c === 38) { // up arrow
                  return 3;
              } else if (c === 13) { // return
                  return 6;
              } else if (c === 40) { // down array
                  return 4;
              } else if (c >= 48 && c<=57) { // 0-9
                  return 1;
              } else if (c >= 97 && c<=102) { // a-f
                  return 2;
              } else if (c >= 65 && c<=70) { // A-F
                  return 2;
              //} else if ("8, 9, 13, 27, 37, 39".indexOf(c) > -1 || 
              //              (c >= 112 && c <=123)) { // including F-keys
              // tab, delete, return, escape, left, right or ctrl/meta sequences
              } else if ("8, 9, 13, 27, 37, 39".indexOf(c) > -1 ||
                         e.ctrlKey || e.metaKey) { // special chars
                  return 5;
              } else { // something we probably don't want
                  return 0;
              }
          }
docs: Key map to well-known commands for txt field input
  @method _getCommand
  @param e {Event} the keypress or keydown event
  @return {int} a command code
  <ul>
  <li>0 = not a number, letter in range, or special key</li>
  <li>1 = number</li>
  <li>2 = a-fA-F</li>
  <li>3 = increment (up arrow)</li>
  <li>4 = decrement (down arrow)</li>
  <li>5 = special key (tab, delete, return, escape, left, right)</li>
  <li>6 = return</li>
  </ul>
  @protected