You can start STA Threads like so:
Thread thread = new Thread(MethodWhichRequiresSTA);
thread.SetApartmentState(ApartmentState.STA); //Set the thread to STA
thread.Start();
thread.Join(); //Wait for the thread to end
The only problem is that your result object must be passed along somehow.. You can use a private field for that, or dive into passing along parameters into threads. Here I set the foo data in a private field and start up the STA Thread to mutate the inkpresenter!
private var foo;
public void SearchForFooCallbackMethod(IAsyncResult ar)
{
foo = GetFooFromAsyncResult(ar);
Thread thread = new Thread(ProcessInkPresenter);
thread.SetApartmentState(ApartmentState.STA);
thread.Start();
thread.Join();
}
private void ProcessInkPresenter()
{
var inkPresenter = XamlReader.Parse(foo.Xaml) as InkPresenter;
}
Hope this helps!