docs: function (target, notifyTargetBehindModalPopup) {
                  var searchPopup = this._document && target !== this._document.body;
                  if (searchPopup) {
                      for (var i = this.openedPopups.length - 1; i >= 0; i--) {
                          var popup = this.openedPopups[i];
                          if (utilsDom.isAncestor(target, popup.getDomElement())) {
                              // the element is in the modal popup, it is fine to focus it
                              return popup;
                          }
                          if (popup.modalMaskDomElement && utilsDom.isAncestor(target, popup.popupContainer.getContainerElt())) {
                              // the element is inside the container for which there is a modal mask
                              if (notifyTargetBehindModalPopup) {
                                  return notifyTargetBehindModalPopup(popup);
                              }
                              return;
                          }
                      }
                  }
              }