Popping a MessageBox for the main app with Backgroundworker in WPF

Question

In a WPF app, I am using a BackgroundWorker to periodically check for a condition on the server. While that works fine, I want to pop a MessageBox notifing the users if something fails during the check.

Here's what I have:

public static void StartWorker()
{
    worker = new BackgroundWorker();

    worker.DoWork += DoSomeWork;
    worker.RunWorkerAsync();
}

private static void DoSomeWork(object sender, DoWorkEventArgs e)
{
    while (!worker.CancellationPending)
    {
        Thread.Sleep(5000);

        var isOkay = CheckCondition();

        if(!isOkay)
           MessageBox.Show("I should block the main window");                
    }   
}

But this MessageBox does not block the main window. I can still click on my WPF app and change anything I like with the MessageBox around.

How do I solve this? Thanks,

---

EDIT:

For reference, this is what I ended up doing:

public static void StartWorker()
{
    worker = new BackgroundWorker();

    worker.DoWork += DoSomeWork;
    worker.ProgressChanged += ShowWarning;
    worker.RunWorkerAsync();
}

private static void DoSomeWork(object sender, DoWorkEventArgs e)
{
    while (!worker.CancellationPending)
    {
        Thread.Sleep(5000);

        var isOkay = CheckCondition();

        if(!isOkay)
           worker.ReportProgress(1);                
    }   
}

private static void ShowWarning(object sender, ProgressChangedEventArgs e)
{
    MessageBox.Show("I block the main window");
}

Answer 1

Call ReportProgress and pass this to MessageBox.Show.