You can use the StartBlockUndoRedo / EndBlockUndoRedo methods to group multiple Undo/Redo operations into a single-block. The GroupUndoRedoActions groups the next to current Undo/Redo Actions in a single block. A block may hold multiple Undo/Redo actions. The AllowUndoRedo property enables or disables the Undo/Redo feature. Use the GroupUndoRedoActions method to group two or more entries in the Undo/Redo queue in a single block, so when a next Undo/Redo operation is performed, multiple actions may occur. For instance, moving several calendar-events in the same time ( multiple calendar-events selection ) is already recorded as a single block. Use the UndoRedoQueueLength property to specify the number of entries that Undo/Redo queue may store.

A block starts with StartBlock and ends with EndBlock when listed by UndoListAction/RedoListAction property as in the following sample:

StartBlock
MoveEvent;B
MoveEvent;A
EndBlock