The OnRedo field is an event handler that is triggered whenever a redo operation is executed within the UndoSystem. It is a public instance field of type System.Action<Sandbox.Helpers.UndoSystem.Entry>, allowing you to attach custom actions that should be performed when a redo occurs.

To use the OnRedo field, you can assign a delegate or lambda expression that matches the signature of System.Action<Sandbox.Helpers.UndoSystem.Entry>. This delegate will be called with the Entry object that represents the redo action being executed.

Example usage:

UndoSystem undoSystem = new UndoSystem();
undoSystem.OnRedo += (entry) => {
    // Custom logic to execute on redo
    Console.WriteLine($"Redo action: {entry.Title}");
};