Sample UI lock sync code for WinForms action invocation (C#)

        private void StartThread()
        {
            lock (this)
            {
                if (!running)
                {
                    running = true;
                    BackgroundWorker bw = new BackgroundWorker();
                    bw.WorkerSupportsCancellation = true;
                    bw.DoWork += bw_DoWork;
                    bw.RunWorkerCompleted += bw_RunWorkerCompleted;
                    cancelAction = () => bw.CancelAsync();
                    bw.RunWorkerAsync();
                }
            }
        }
        private void StopThread()
        {
            lock (this)
            {
                if (running)
                {
                    running = false;
                }
            }
        }
        void bw_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
            StopThread();
        }
        void bw_DoWork(object sender, DoWorkEventArgs e)
        {
            Invoke(() => MessageBox.Show(this, "Несём мессадж в массы", this.Text), false);
        }