code: function _fnGetFocusControlById(oToolPopup, id) {
                  var oControl,
                      parent;
  
                  if (!id) {
                      return null;
                  }
  
                  oControl = sap.ui.getCore().byId(id);
  
                  while (!oControl && oControl !== oToolPopup) {
                      if (!id || !document.getElementById(id)) {
                          return null;
                      }
                      parent = document.getElementById(id).parentNode;
                      id = parent.id;
                      oControl = sap.ui.getCore().byId(id);
                  }
                  return oControl;
              }
docs: Returns a DOM element by its Id.
  
  @param {Number} id
  @returns {Element|sap.ui.core.Element|Object|sap.ui.core.tmpl.Template}
  @private