C# passing reference array from class to form

public static void AddLine(string msg)
{
    _staticForm.AddLineInternal(msg);
}

delegate void AddLineDelegate(string msg);
void AddLineInternal(string msg)
{
    if (InvokeRequired)
        Invoke(new AddLineDelegate(AddLineInternal), msg);
    else
    {
        textBox1.Text += msg + Environment.NewLine;
        // flytta markören till slutet av textboxen
        textBox1.SelectionStart = textBox1.Text.Length;
        textBox1.ScrollToCaret();
    }
}