code: function _ensurePaneIsFocused(paneId) {
          var pane = MainViewManager._getPane(paneId);
  
          // Defer the focusing until other focus events have occurred.
          setTimeout(function () {
              // Focus has most likely changed: give it back to the given pane.
              pane.focus();
              this._lastFocusedElement = pane.$el[0];
              MainViewManager.setActivePaneId(paneId);
          }, 1);
      }
docs: Ensures that the given pane is focused after other focus related events occur
  @params {string} paneId - paneId of the pane to focus
  @private