C# Threads - Parent Access Problem

Question

my aim is that in the function "Dummy" i can change the controls like labels etc of the form from which the thread is initiating..how to do it..please don't suggest completely different strategies or making a worker class etc...modify this if you can

        Thread pt= new Thread(new ParameterizedThreadStart(Dummy2));


        private void button1_Click(object sender, EventArgs e)
        {                    
            pt = new Thread(new ParameterizedThreadStart(Dummy2));
            pt.IsBackground = true;
            pt.Start( this );
        }


        public static void Dummy(........)
        {
           /*                
           what i want to do here is to access the controls on my form form where the
           tread was initiated and change them directly
           */ 
        }

        private void button2_Click(object sender, EventArgs e)
        {
            if (t.IsAlive)
                label1.Text = "Running";
            else
                label1.Text = "Dead";
        }

        private void button3_Click(object sender, EventArgs e)
        {
            pt.Abort();
        }


    }
}

what i plan is that i could do this in the "Dummy" function

Dummy( object p)
{
  p.label1.Text = " New Text " ;
}

Answer 1

You can't do this. You can only access a UI control on the same thread that created it.

See the System.Windows.Forms.Control.Invoke Method and the Control.InvokeRequired property.

Answer 2

Can use something like this:

private void UpdateText(string text)
{
    // Check for cross thread violation, and deal with it if necessary
    if (InvokeRequired)
    {
        Invoke(new Action<string>(UpdateText), new[] {text});
        return;
    }

    // What the update of the UI
    label.Text = text;
}

public static void Dummy(........)
{
   UpdateText("New text");
}

Answer 3

You could do this, supposing you're passing an instance of the form to the thread method using the t.Start(...) method:

private void Form_Shown(object sender)
{
    Thread t = new Thread(new ParameterizedThreadStart(Dummy));
    t.Start(this);
}

....


private static void Dummy(object state)
{
    MyForm f = (MyForm)state;

    f.Invoke((MethodInvoker)delegate()
    {
        f.label1.Text = " New Text ";
    });
}

EDIT
Added thread start code for clarity.