add:  if (!this._view.rowCount) this.clear(); 
context:   onPermissionDeleted: function ()  {    if (!this._view.rowCount)      return;    var removedPermissions = [];    gTreeUtils.deleteSelectedItems(this._tree, this._view, this._permissions, removedPermissions);    for (var i = 0; i < removedPermissions.length; ++i) {      var p = removedPermissions[i];      this._pm.remove(p.host, p.type);    }        document.getElementById("removePermission").disabled = !this._permissions.length;    document.getElementById("removeAllPermissions").disabled = !this._permissions.length;  },
meta: 8395	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/8395/fd59bc997472e2f621d2dd4151cb0651ec8afd16/xforms-permissions.js/clean/extensions/xforms/resources/content/xforms-permissions.js