Mission planner:

* Added timeout to udp port open
    * Disabled baud selector for udp
    * Fixed problem where selected port might disappear when clicking near
      the port selector

Tools/ArdupilotMegaPlanner/CommsUdpSerial.cs

@@ -79,6 +79,18 @@ namespace System.IO.Ports
 
             client = new UdpClient(int.Parse(Port));
 
+            int timeout = 5;
+            while (timeout > 0)
+            {
+                if (BytesToRead > 0)
+                    break;
+                System.Threading.Thread.Sleep(1000);
+                timeout--;
+            }
+
+            if (BytesToRead == 0)
+                return;
+
             try
             {
                 client.Receive(ref RemoteIpEndPoint);

Tools/ArdupilotMegaPlanner/MainV2.cs

@@ -222,9 +222,12 @@ namespace ArdupilotMega
 
         private void CMB_serialport_Click(object sender, EventArgs e)
         {
+            String old_port = CMB_serialport.Text;
             CMB_serialport.Items.Clear();
             CMB_serialport.Items.AddRange(SerialPort.GetPortNames());
             CMB_serialport.Items.Add("UDP");
+            if (CMB_serialport.Items.Contains(old_port))
+                CMB_serialport.Text = old_port;
         }
 
         public static void fixtheme(Control temp)
@@ -672,6 +675,10 @@ namespace ArdupilotMega
         private void CMB_serialport_SelectedIndexChanged(object sender, EventArgs e)
         {
             comportname = CMB_serialport.Text;
+            if (comportname == "UDP")
+                CMB_baudrate.Enabled = false;
+            else
+                CMB_baudrate.Enabled = true;
             try
             {
                 comPort.BaseStream.PortName = CMB_serialport.Text;