public async static Task InstanceAsync(Window owner, Task worker)
{
WorkingWindow W = new WorkingWindow();
W.Owner = owner;
CancellationToken token = new CancellationToken();
Task InitWinTask = Task.Factory.StartNew(
() => W.ShowDialog(),
token,
TaskCreationOptions.None,
TaskScheduler.FromCurrentSynchronizationContext());
worker.Start();
await worker;
W.Close();
await InitWinTask;
}
