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* The nsITransaction interface.
* This interface is implemented by an object that needs to
* execute some behavior that must be tracked by the transaction manager.
interface nsITransaction : nsISupports
* Executes the transaction.
* Restores the state to what it was before the transaction was executed.
* Executes the transaction again. Can only be called on a transaction that
* was previously undone.
* In most cases, the redoTransaction() method will actually call the
* doTransaction() method to execute the transaction again.
* The transaction's transient state. This attribute is checked by
* the transaction manager after the transaction's Execute() method is called.
* If the transient state is false, a reference to the transaction is
* held by the transaction manager so that the transactions' undoTransaction()
* and redoTransaction() methods can be called. If the transient state is
* true, the transaction manager returns immediately after the transaction's
* doTransaction() method is called, no references to the transaction are
* maintained. Transient transactions cannot be undone or redone by the
* transaction manager.
readonly attribute boolean isTransient;
* Attempts to merge a transaction into "this" transaction. Both transactions
* must be in their undo state, doTransaction() methods already called. The
* transaction manager calls this method to coalesce a new transaction with
* the transaction on the top of the undo stack.
* This method returns a boolean value that indicates the merge result.
* A true value indicates that the transactions were merged successfully,
* a false value if the merge was not possible or failed. If true,
* the transaction manager will Release() the new transacton instead of
* pushing it on the undo stack.
* @param aTransaction the previously executed transaction to merge.
boolean merge(in nsITransaction aTransaction);