B2G/gecko/browser/devtools/shared/Undo.jsm
/**
   * Start a collection of related changes.  Changes will be batched
   * together into one undo/redo item until endBatch() is called.
   *
   * Batches can be nested, in which case the outer batch will contain
   * all items from the inner batches.  This allows larger user
   * actions made up of a collection of smaller actions to be
   * undone as a single action.
   */
Start a collection of related changes.  Changes will be batched
together into one undo/redo item until endBatch() is called.

Batches can be nested, in which case the outer batch will contain
all items from the inner batches.  This allows larger user
actions made up of a collection of smaller actions to be
undone as a single action.
Start a collection of related changes . Changes will be batched together into one undo / redo item until endBatch () is called . Batches can be nested in which case the outer batch will contain all items from the inner batches . This allows larger user actions made up of a collection of smaller actions to be undone as a single action .
function Undo_startBatch()
  {
    if (this._batchDepth++ === 0) {
      this._batch = [];
    }
  }
function Undo_startBatch ( ) { if ( this . _batchDepth ++ === 0 ) { this . _batch = [ ] ; } }
Start a collection of related changes.
Start a collection of related changes .