# IOleParentUndoUnit::Open

Opens a new parent undo unit, which becomes part of the containing unit’s undo stack.

HRESULT Open(

IOleParentUndoUnit* pPUU | //Pointer to the parent undo unit to open
); |

Parameters

pPUU
  [in] Pointer to the parent undo unit to be opened.

Return Values

S_OK
  The parent undo unit was successfully opened or it is currently blocked.

Remarks

The specified parent unit is created and remains open. The undo manager then calls the Add or Open methods on this parent unit to add new units to it. This parent unit receives any additional undo units until its Close method is called.

The parent unit specified by pPUU is not added to the undo stack until its Close method is called with the fCommit parameter set to TRUE.

The parent undo unit or undo manager must contain any undo unit given to it unless it is blocked. If it is blocked, it must return S_OK but should do nothing else.

See Also

IOleUndoManager::Open