Thread-safe updates of a WinForm control from other classes

Question

Could someone please help me with the following problem:

There are two classes MainForm and LWriter. Below is a method from the LWriter that in addition to writing

Answer 1

delegate can be used for Thread safe calls

Check this http://msdn.microsoft.com/en-us/library/ms171728.aspx

            // This delegate enables asynchronous calls for setting
    // the text property on a TextBox control.
    delegate void SetTextCallback(string text);

    // This method demonstrates a pattern for making thread-safe
    // calls on a Windows Forms control. 
    //
    // If the calling thread is different from the thread that
    // created the TextBox control, this method creates a
    // SetTextCallback and calls itself asynchronously using the
    // Invoke method.
    //
    // If the calling thread is the same as the thread that created
    // the TextBox control, the Text property is set directly. 

    private void SetText(string text)
    {
        // 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.textBox1.InvokeRequired)
        {   
            SetTextCallback d = new SetTextCallback(SetText);
            this.Invoke(d, new object[] { text });
        }
        else
        {
            this.textBox1.Text = text;
        }
    }