窗口究竟发生了什么形成线程

在异步 OnMsgRecieved 调用中，如果我直接将值分配给控件，则它不起作用。然后我知道这是由于线程不安全，我得到了以下代码来解决问题。现在它正在工作。但我不确定它实际上做了什么。谁能让我完全理解它？代码是：-

        public void listener_OnMsgRecieved(string aResponse)
    {
        ShowResponseMessage(aResponse);
    }
    public void ShowResponseMessage(string aResponse)
    {
        // InvokeRequired required compares the thread ID of the
        // calling thread to the thread ID of the creating thread.
        // If these threads are different, it returns true.
        if (this.listBox.InvokeRequired)
        {
            SetTextCallback d = new SetTextCallback(ShowResponseMessage);
            this.Invoke(d, new object[] { aResponse });
        }
        else
        {
            this.listBox.Items.Add(aResponse);
            label.Text = "Response received from Server :";
        }
    }