By default, the UndoRedoQueueLength property is -1. Use the UndoRedoQueueLength property to specify the number of entries that Undo/Redo queue may store. For instance, if the UndoRedoQueueLength property is 1, the control retains only the last control operation. Changing the UndoRedoQueueLength property may change the current Undo/Redo queue based on the new length. The length being specified, does not affect the blocks in the queue. A block may hold multiple Undo/Redo actions. 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 bars in the same time ( multiple bars selection ) is already recorded as a single block.