IOleParentUndoUnit::Open method (ocidl.h)

Article
10/13/2021

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

Syntax

HRESULT Open(
  [in] IOleParentUndoUnit *pPUU
);

Parameters

[in] pPUU

An IOleParentUndoUnit pointer to the parent undo unit to be opened.

Return value

This method returns S_OK if 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 IOleParentUndoUnit::Add or IOleParentUndoUnit::Open methods on this parent unit to add new units to it. This parent unit receives any additional undo units until its IOleParentUndoUnit::Close method is called.

The parent unit specified by pPUU is not added to the undo stack until its IOleParentUndoUnit::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.

Requirements

Requirement	Value
Minimum supported client	Windows 2000 Professional [desktop apps only]
Minimum supported server	Windows 2000 Server [desktop apps only]
Target Platform	Windows
Header	ocidl.h