Method doesn't return controlling

Question

I have a grid on WPF form and another class, that has some events. From my wpf form i subscribe on those events and i want them to add some objects to my grid, but only that i have is "The calling thread cannot access this object because a different thread owns it." How can I avoid this proble and get same functionality?

Answer 1

This has been covered ad nauseam on StackOverflow and elsewhere. You need to use the Dispatcher to marshal your access back to the UI thread. For example:

private void OnSomeEvent(object sender, EventArgs e)
{
    // this is being called on a thread other than the UI thread so marshal back to the UI thread
    Dispatcher.BeginInvoke((ThreadStart)delegate
    {
        // now the grid can be accessed
        grid.Whatever = foo;
    });
}

Answer 2

This is a cross-threading issue. Look into delegate creation so you can safely invoke another thread to modify something that was created on the different thread. Here is a good MSDN article about how to make these thread-safe calls.

http://msdn.microsoft.com/en-us/library/ms171728(v=vs.80).aspx