How to update a control on WPF MainWindow

Question

How do I update my label1 text in the code below ? I am getting a "The calling thread cannot access this object because a different thread owns it" error. I have read that others have used Dispatcher.BeginInvoke but I do not know how to implement it in my code.

public partial class MainWindow : Window
{
    System.Timers.Timer timer;

    [DllImport("user32.dll")]        
    public static extern Boolean GetLastInputInfo(ref tagLASTINPUTINFO plii);

    public struct tagLASTINPUTINFO
    {
        public uint cbSize;
        public Int32 dwTime;
    }

    public MainWindow()
    {
        InitializeComponent();
        StartTimer();
        //webb1.Navigate("http://yahoo.com");
    }

    private void StartTimer()
    {
        timer = new System.Timers.Timer();
        timer.Interval = 100;
        timer.Elapsed += timer_Elapsed;
        timer.Start();
    }

    void timer_Elapsed(object sender, System.Timers.ElapsedEventArgs e)
    {
        tagLASTINPUTINFO LastInput = new tagLASTINPUTINFO();
        Int32 IdleTime;
        LastInput.cbSize = (uint)Marshal.SizeOf(LastInput);
        LastInput.dwTime = 0;

        if (GetLastInputInfo(ref LastInput))
        {
            IdleTime = System.Environment.TickCount - LastInput.dwTime;
            string s = IdleTime.ToString();
            label1.Content = s;
        } 
    }
}

Answer 1

You can try something like this:

if (GetLastInputInfo(ref LastInput))
{
    IdleTime = System.Environment.TickCount - LastInput.dwTime;
    string s = IdleTime.ToString();

    Dispatcher.BeginInvoke(new Action(() =>
    {
        label1.Content = s;
    }));
}

Read more about Dispatcher.BeginInvoke Method here