跨线程 UI - 动态控件

我的WinForms应用程序需要一个加载面板。我正在使用此处找到的示例

（flowLayoutPanel1 位于 UI 线程上 示例中替换 Thread.Sleep 的异步委托代码类似于下面的代码。我收到跨线程错误，将我的动态控件添加到流面板）

AsyncProcessDelegate d = delegate() {
     flowLayoutPanel1.Controls.Clear();
Panel p1 = new Panel();
Button btn1 = new Button();
        p1.Controls.Add(btn1);
        //tried to access from another thread
        flowLayoutPanel1.Controls.Add(p1);
        // Just in case it's not clear, I already know this does not work
        // The question is how can I make the example wait for my UI to load
        // if I can't do the dynamic control creation as shown.
  };
  RunAsyncOperation(d);

this.Control.CheckForIllegalCrossThreadCalls=false;