WPF SelectionChanged event do the action before tab change

Question

i have SelectionChanged event in my WPF aplication. i want that when the tab is change to do some action but first i want the tab to visualy change before the action starts. i am using background worker to do the job. my code is:

    private void Tab_SelectionChanged(object sender, SelectionChangedEventArgs e)
    {
        if (tab1.IsSelected)
        {
            //this line is not working
            tabcontrol.SelectedIndex = 1;
            wNetTest = new BackgroundWorker();
            wNetTest.DoWork += new DoWorkEventHandler(worker_DoWork);
            wNetTest.RunWorkerCompleted += worker_RunWorkerCompleted;
            wNetTest.WorkerReportsProgress = true;
            wNetTest.WorkerSupportsCancellation = true;
            wNetTest.RunWorkerAsync();

        }
    }

    void worker_DoWork(object sender, DoWorkEventArgs e)
    {
        //do the job
    }

Answer 1

Your problem is that your code is running synchronously. Therefore, every line of your Tab_SelectionChanged event handler will run before you will see the TabItem change. To fix this problem, you just need to run your long running process asynchronously. One of the simplest ways to do that is this:

private void Tab_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
    if (tab1.IsSelected)
    {
        //this line is not working
        tabcontrol.SelectedIndex = 1;
        Task.Factory.StartNew(() => LongRunningMethod(parameter));

    }
}

private void LongRunningMethod(object parameter)
{
    // perform long running process here
}

The parameter input parameter is optional... just remove it if you don't need it.