Stopping a long-running asynchronous computation

I'm writing a program that will perform a long-running computation, gradually improving a solution. On top of that, there's a simple UI that basically allows the user to stop the computation (letting the worker finish a step it's working on) and shows the best solution.
Here's a simplified version of what I have, I'm using async/await for the first time. Is there anything you would improve, or any other comments?

Worker code

public class SearchEngine
{
    //...
    public async Task Search(CancellationTokenSource cts)
    {
        await Task.Factory.StartNew(() => {
            BestSolution = Problem.RandomSolution();
            while (!cts.IsCancellationRequested)
            {
                IProblemSolution s = Problem.RandomSolution(); // for simplification 
                if (s.ObjectiveValue() < BestSolution.ObjectiveValue())
                    BestSolution = s;
            }
        });
        return BestSolution;
    }
}

UI

private async void StartButton_Click(object sender, RoutedEventArgs e)
    {
        if (CancelTokenSrc != null)
            return;

        CancelTokenSrc = new CancellationTokenSource();
        Engine = new SearchEngine(new SampleProblem());

        StopButton.IsEnabled = true;
        StartButton.IsEnabled = false;
        Task t = Engine.Search(CancelTokenSrc);
        await t;

        ResultLabel.Content = t.Result.ObjectiveValue().ToString();
        StopButton.IsEnabled = false;
        StartButton.IsEnabled = true;
        CancelTokenSrc = null;
    }

    private void StopButton_Click(object sender, RoutedEventArgs e)
    {
        if (CancelTokenSrc != null)
            CancelTokenSrc.Cancel();
    }

Task-based Asynchronous Pattern (MSDN)

public async Task Search(CancellationTokenSource cts)

As I explain in this answer, one would rightfully expect the signature of that method to read like this:

public async Task SearchAsync(CancellationTokenSource cts)

The pattern for async methods is quite simple: use the async keyword, return Task or Task, and put an "Async" suffix to the method's name.

I haven't written much async code (read: never wrote a line of C# that leverages features of .net 4.5), but from previous reviews of such code I think this:

Task t = Engine.Search(CancelTokenSrc);
    await t;

    ResultLabel.Content = t.Result.ObjectiveValue().ToString();

Could be written like this:

var searchResult =  await Engine.SearchAsync(CancelTokenSrc);
    ResultLabel.Content = searchResult.ObjectiveValue().ToString();
    //...

My understanding is that await somehow deals with Task.Result and so the type of searchResult would be IProblemSolution - I might be wrong here though.

Other than that, I find you could give var some lovin', and change this:

IProblemSolution s = Problem.RandomSolution();

To this:

var s = Problem.RandomSolution();

Lastly, I might be biased because I use ReSharper and with that tool IntelliSense/auto-complete is much "smarter", but I don't like names like cts - I'd rather call it cancelTokenSource and then I can type ctsTab and poof I'm referring to a readable identifier with a pronounceable name.

StackExchange Code Review Q#45838, answer score: 2