This class wraps the IOleUndoManager from Visual Studio and adds undo unit merging.
Assembly: Microsoft.VisualStudio.GraphModel (in Microsoft.VisualStudio.GraphModel.dll)
Pushes the specified undo unit onto the undo stack.
Adds an undo unit to the undo stack, potentially merging it with other undo units on the stack or dropping it if it is empty. If it has UndoOption.AddForce, it will always be added, even if it is empty. This is useful for compound operations such as moving nodes, drag/drop or label editing where you merge a series of undo units into one atomic unit and you must have a sure way of starting with the Add unit even if it is at first empty.
Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.