Application.DoEvent() 使ってるので負けな気持ちだけど、memoしとく。Application.DoEvent() 使わない為にはどーすればええんだろか。

RunSyncForWinForm.cs

/// <summary>
/// 非同期 -> 固まらない同期
/// </summary>
/// <typeparam name="T">非同期処理の戻りの型</typeparam>
/// <param name="RunAsync">非同期処理</param>
/// <param name="Factory">スレッドを選択するファクトリー</param>
/// <param name="Waiter">待つ為の関数</param>
/// <returns></returns>
private static T RunSync<T>(Func<Task<T>> RunAsync, TaskFactory Factory = null, Action Waiter = null)
{
    var taskComp = new HashSet<TaskStatus>(new[] { TaskStatus.RanToCompletion, TaskStatus.Canceled, TaskStatus.Faulted });
    var task = (Factory ?? Task.Factory).StartNew(async () => await RunAsync()).Unwrap();
    if (Waiter == null)
        Waiter = System.Windows.Forms.Application.DoEvents;
    while (!taskComp.Contains(task.Status))
        Waiter();
    switch (task.Status)
    {
        case TaskStatus.RanToCompletion:
            return task.Result;
        case TaskStatus.Faulted:
            System.Runtime.ExceptionServices.ExceptionDispatchInfo.Capture(task.Exception.InnerException).Throw();
            break;
        case TaskStatus.Canceled:
            throw new TaskCanceledException();
    }
    return default(T);
}
/// <summary>
/// 非同期 -> 固まらない同期
/// </summary>
/// <param name="RunAsync">非同期処理</param>
/// <param name="Factory">スレッドを選択するファクトリー</param>
/// <param name="Waiter">待つ為の関数</param>
private static void RunSync(Func<Task> RunAsync, TaskFactory Factory = null, Action Waiter = null)
{
    var taskComp = new HashSet<TaskStatus>(new[] { TaskStatus.RanToCompletion, TaskStatus.Canceled, TaskStatus.Faulted });
    var task = (Factory ?? Task.Factory).StartNew(async () => await RunAsync()).Unwrap();
    if (Waiter == null)
        Waiter = System.Windows.Forms.Application.DoEvents;
    while (!taskComp.Contains(task.Status))
        Waiter();
    switch (task.Status)
    {
        case TaskStatus.RanToCompletion:
            return;
        case TaskStatus.Faulted:
            System.Runtime.ExceptionServices.ExceptionDispatchInfo.Capture(task.Exception.InnerException).Throw();
            break;
        case TaskStatus.Canceled:
            throw new TaskCanceledException();
    }
    return;
}