async/await

gistfile1.cs

private void Button_Click_1( object sender, RoutedEventArgs e )
        {
            //HeavyProcess();
            var stopwatch = Stopwatch.StartNew();
            var stopwatch2 = Stopwatch.StartNew();
            this.button1.IsEnabled = false; //prevent re-entry 
            var someTask = Task<Task<int>>.Factory.StartNew( () => slowFunc( 1, 2 ) );
            someTask.ContinueWith( x =>
            {
                this.label1.Text = "Result: " + someTask.Result.Result.ToString();
                this.button1.IsEnabled = true;
                stopwatch2.Stop();
            },
            TaskScheduler.FromCurrentSynchronizationContext() );
            //this.label1.Text = "Result: " + someTask.Result.Result.ToString(); //oops, blocks calling thread 
            //this.button1.IsEnabled = true;
            stopwatch.Stop();

            new MessageDialog( string.Format( "{0}ms, {1}ms", stopwatch.ElapsedMilliseconds, stopwatch2.ElapsedMilliseconds ) ).ShowAsync();
        }

 private async Task<int> slowFunc( int a, int b )
        {
            await Task.Delay( TimeSpan.FromSeconds( 5 ) );
            return a + b;
        }