C#

private void NewChildForm()
{
    ChildForm child = new ChildForm();
    child.MdiParent = this;
    child.SizeChanged += new EventHandler(this.childForm_SizeChanged);
}

private void childForm_SizeChanged(object sender, EventArgs e)
{
    Form child = sender as Form;
    this.Size = new Size(child.Width, child.Height);
}

C-P-User-3 wrote:

this is ridiculously complex.

C-P-User-3 wrote:

It is the light I've been after. Thanks.

C-P-User-3 wrote:

I do not understand what thread the debugger has in mind, because I didn't start a thread.

"...The next part is critical and not obvious. serialPort1 runs in it own separate thread behind the scenes..."   

Application.Run(new Form1());

TheActivePortWeAreUsing.Write(TheBytesToSend, StartingPosition, Length);

System.Timers.Timer tmrPortInt = new System.Timers.Timer(800);
 comportInt.DataReceived += new SerialDataReceivedEventHandler(portInt_DataReceived);
 tmrPortInt.Elapsed += new System.Timers.ElapsedEventHandler(tmrPortInt_Elapsed);

 private void portInt_DataReceived(object sender, SerialDataReceivedEventArgs e)
        {
            if (tmrPortInt.Enabled) tmrPortInt.Stop();//this is a timer to check if no more data is received,
                                                      //While data is received within 800 m Sec port keeps listening.
                                                      // In my case he data is processed in the timer elapsed event(~6000 bytes).
            int tempAddress;
            int bytes = comportInt.BytesToRead;
            byte[] buffer = new byte[3];  //I want to read only three bytes.

            if (bytes > 2)
            {
                buffer = new byte[bytes]; //Empty my buffer before filling with received bytes.
                comportInt.Read(buffer, 0, 3);
               
                comportInt.Write(buffer, 2, 1);//You can see i am writing within the port_received event.
                                               // I send the third byte received.
                if (receiveByteList == null) receiveByteList = new List<byte>();
               
                tempAddress = (256 * buffer[0] + buffer[1]); // decimal value of two address bytes
                receiveBytes[tempAddress] = buffer[2];
                receiveByteList.Add(receiveBytes[1]);// add data byte to list
               
                tmrPortInt.Start();// Prevents the timer to elapse until no more bytes are received.
            }
        }
         void tmrPortInt_Elapsed(object sender, System.Timers.ElapsedEventArgs e)
        {
            tmrPortInt.Stop();
            this.Invoke(new EventHandler(Process_MachineData));// This is where I do something With the data received.
        }