[ghuntley]

Hah; check out RX & http://reactiveui.net/ which is the framework behind GitHub for Windows. You will never have to worry about which thread your running on ever again. Doesn't just support WPF - it also works on Windows Phone, iPhone, Mac OSX & Android:

    public SearchViewModel(ISearchService searchService = null) : ReactiveObject, IRoutableViewHost
    {
        SearchService = searchService ?? Locator.Current.GetService<ISearchService>();
     
        // Here we're describing here, in a *declarative way*, the conditions in
        // which the Search command is enabled.  Now our Command IsEnabled is
        // perfectly efficient, because we're only updating the UI in the scenario
        // when it should change.
        var canSearch = this.WhenAny(x => x.SearchQuery, x => !String.IsNullOrWhiteSpace(x.Value));
     
        // ReactiveCommand has built-in support for background operations and
        // guarantees that this block will only run exactly once at a time, and
        // that the CanExecute will auto-disable and that property IsExecuting will
        // be set according whilst it is running.
        Search = ReactiveCommand.CreateAsyncTask(canSearch, async _ => {
            return await searchService.Search(this.SearchQuery);
        });
     
        // ReactiveCommands are themselves IObservables, whose value are the results
        // from the async method, guaranteed to arrive on the UI thread. We're going
        // to take the list of search results that the background operation loaded, 
        // and them into our SearchResults.
        Search.Subscribe(results => {
            SearchResults.Clear();
            SearchResults.AddRange(results);
        });
     
        // ThrownExceptions is any exception thrown from the CreateAsyncTask piped
        // to this Observable. Subscribing to this allows you to handle errors on
        // the UI thread. 
        Search.ThrownExceptions
            .Subscribe(ex => {
                UserError.Throw("Potential Network Connectivity Error", ex);
            });
     
        // Whenever the Search query changes, we're going to wait for one second
        // of "dead airtime", then automatically invoke the subscribe command.
        this.WhenAnyValue(x => x.SearchQuery)
            .Throttle(TimeSpan.FromSeconds(1), RxApp.MainThreadScheduler)
            .InvokeCommand(this, x => x.Search);
    }

[zamalek]

"Not worrying about the thread" is actually a feature of TPL. A SynchronizationContext[1] is stored in thread local storage for UI threads, which can be used to queue calls back to that thread (a .Net 2.0 feature). When you `await` something, TPL takes advantage of the original SynchronizationContext and the callback will be automatically made on the UI thread.

If you implement SynchronizationContext and set it, you can actually have the TPL call back into whatever special threading stuff you want.

It doesn't work for WPF bindings, but for the quick'n'dirty procedural UI code it works great.

[1]: https://msdn.microsoft.com/en-us/library/system.threading.sy...