code: function(signal, slot) {
              if (signal.charAt(0) == '@') {
                  // Registering a global signal.
                  $$.statics("WTag").globalSlots[signal] = [this, slot];
              } else {
                  this._slots[signal] = slot;
              }
          }
docs: Register a  listener (the  function "slot") for  the signal
  "signal". If  this slot  returns true, the  signal continue
  its ascension towards parent widgets.
  
  @param signal Name of the signal to catch.
  @param slot Function to call to process this signal
  @memberof WTag
  @inner
  @memberof WTag