Async in winforms kinda sux Here is a way better way to do it

gistfile1.cs

//static for extension..
//this allows us to always make sure we're using our controls on the 
//thread they were created on, regardless of the thread we're calling from...
public static class ISynchronizeInvokeExtensions
{
   public static void InvokeEx<T>(this T @this, Action<T> action) where T : ISynchronizeInvoke
   {
       if (@this.InvokeRequired)
           @this.BeginInvoke(action, new object[] { @this });
       else
           action(@this);
   }
} ​

//So now you can call it like:

Txtbox.InvokeEx​(txt => {

   txt.Text = "blah";

});