Windows:
delegate void DelegateSetValue(Button btn, string value);
private void TheTime()
{
    DelegateSetValue d = new DelegateSetValue(SetValue);
    btnSearch.Invoke(d, btnSearch, "忙**");
    Thread.Sleep(1000);
    btnSearch.Invoke(d, btnSearch, "搜索");
}
private void SetValue(Button btn, string value)
{
    btn.Text = value;
}

WPF:
private delegate void DelegateSetValue(Button btn, string value);
private void TheTime()
{
    Delegate d = Delegate.CreateDelegate(typeof(DelegateSetValue),this,"SetValue");
    btnSearch.Dispatcher.Invoke(DispatcherPriority.Normal, d, btnSearch, "忙..");
    Thread.Sleep(1000);
    btnSearch.Dispatcher.Invoke(DispatcherPriority.Normal, d, btnSearch, "搜索");
}
private void SetValue(Button btn, string value)
{
    btn.Content = value;
}

Silverlight:
delegate void DelegateSetValue(Button btn, string value);
private void TheTime()
{
    DelegateSetValue d = new DelegateSetValue(SetValue);
    btnSearch.Dispatcher.BeginInvoke(d, btnSearch, "忙--");
    Thread.Sleep(1000);
    btnSearch.Dispatcher.BeginInvoke(d, btnSearch, "搜索");
}
private void SetValue(Button btn, string value)
{
    btn.Content = value;
}