FastColoredTextBoxNS.CommandManager.Undo C# (CSharp) Method

        public void Undo()
        {
            if (history.Count > 0)
            {
                var cmd = history.Pop();
                //
                BeginDisableCommands();//prevent text changing into handlers
                try
                {
                    cmd.Undo();
                }
                finally
                {
                    EndDisableCommands();
                }
                //
                redoStack.Push(cmd);
            }

            //undo next autoUndo command
            if (history.Count > 0)
            {
                if (history.Peek().autoUndo)
                    Undo();
            }

            TextSource.CurrentTB.OnUndoRedoStateChanged();
        }