in my app' i'm recieving data from serial port and save them into two bool arrays.
And depends on these array i'm setting checkboxes. But checkboxes are not updating only when i change the tabs....

Here's how i'm doin' it(maybe there's better way how to do it)

private void comboBoxCommunication_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
    if (serialPort.IsOpen)
  {
    recieveThread.Abort();
        serialPort.Close();               
  }
  ComboBoxItem cbi = (ComboBoxItem)comboBoxCommunication.SelectedItem;
  portCommunication = cbi.Content.ToString();
  serialPort.PortName = portCommunication;
  try
  {
    serialPort.Open();
    recieveThread = new Thread(dataRecieving);
        prijmiThread.Start();                                
    checkBoxI1.IsChecked = vstupy[0] ? true : false;
    checkBoxI2.IsChecked = inputs[1] ? true : false;
    checkBoxI3.IsChecked = inputs[2] ? true : false;
    checkBoxQ2.IsChecked = outputs[3] ? true : false;                                           
  }
  catch (IOException ex)
  {
        MessageBox.Show(ex.ToString(), "Error!", MessageBoxButton.OK, MessageBoxImage.Error, MessageBoxResult.OK);
    }
}

private void dataRecieving()
{ 
    if (serialPort.IsOpen)
  {                    
    int i = serialPort.ReadChar();
    if (i == 'A')
    {
        inputs[0] = true;
    }
        else if (i == 'a')
        {
        inputs[0] = false;
    }
    if (i == 'B')
    {
        inputs[1] = true;
    }
    else if (i == 'b')
    {
        inputs[1] = false;
    }
    if (i == 'C')
    {
        inputs[2] = true;
    }
    else if (i == 'c')
    {
        inputs[2] = false;
    }
    if (i == 'D')
    {
        outputs[0] = true;
    }
    else if (i == 'd')
    {
        outputs[0] = false;
    }                        
  }           
}