The OnRedo field is an event handler that is triggered whenever a redo operation is executed within the UndoSystem. This field is of type System.Action<UndoSystem.Entry>, allowing you to attach custom actions that should occur when a redo is performed.

To use the OnRedo field, you can subscribe to it by adding a method that matches the System.Action<UndoSystem.Entry> delegate signature. This method will be called with the UndoSystem.Entry that is being redone.

Example usage:

UndoSystem undoSystem = new UndoSystem();
undoSystem.OnRedo += entry => {
    // Custom logic to execute when a redo is performed
    Console.WriteLine($"Redoing: {entry.Title}");
};