如何在ToolTip

Question

我开发了一个控件，并将其用作工具提示。

我需要在ToolTip中添加一个控件。所以我在工具提示控件的OnLayout中添加了要添加到工具提示中的控件。控制正在增加罚款。但添加的控件不是第一次渲染。仅从第二次渲染才显示。

public ToolTipControl : Control
{
   NativeToolTip.TOOLINFO toolInfo;

   public ToolTipControl()
   {
      toolInfo = new NativeToolTip.TOOLINFO();
      toolInfo.cbSize = (uint)Marshal.SizeOf(toolInfo);
      toolInfo.uFlags = WindowMessages.TTF_IDISHWND;
      toolInfo.hwnd = IntPtr.Zero;
      toolInfo.uId = IntPtr.Zero;
      toolInfo.rect = new NativePaint.RECT();
      toolInfo.hinst = IntPtr.Zero;
      toolInfo.lpszText = (IntPtr)Marshal.StringToHGlobalAuto("tooltip");
      toolInfo.lParam = IntPtr.Zero;

   }

   public void SetToolTip(Control control)
   {
       if (control == null)
           return;

       control.HandleCreated += OnControlHandleCreated;

       if (control.IsHandleCreated)
           OnControlHandleCreated(control, EventArgs.Empty);
    }


    private void OnControlHandleCreated(object sender, EventArgs e)
    {
       Control control = sender as Control;

       if (control == null)
          return;

       toolInfo.hwnd = this.Handle;
       toolInfo.uId = control.Handle;

       NativeToolTip.SendMessage(this.Handle, WindowMessages.TTM_ADDTOOLW, 0, ref toolInfo);
    }

    protected override CreateParams CreateParams
    {
       get
       {
          CreateParams param = base.CreateParams;
          param.ClassName = "tooltips_class32";
          param.Style = unchecked(WindowMessages.WS_POPUP) | WindowMessages.TTS_ALWAYSTIP;
          param.ExStyle |= WindowMessages.WS_EX_TOPMOST;
          return param;
       }
    }

    protected override void WndProc(ref Message m)
    {
       base.WndProc(ref m);
       switch (m.Msg)
       {
          case (int)WindowMessages.WM_NOTIFY:
          {
             NativeToolTip.NMHDR hdr = (NativeToolTip.NMHDR)Marshal.PtrToStructure(m.LParam, typeof(NativeToolTip.NMHDR));
             switch (hdr.code)
             {
                case (int)WindowMessages.TTN_SHOW:
                    OnPopup(GetControl(hdr.hwndFrom, (IntPtr)hdr.idFrom), ref m);
                    return;

             }
        }
    }    

    void OnPopup(Control control, ref Message m)
    {
       Info info = this.GetInfo(control);

       if (info == null)
           return;

       this.Info = info;
       this.PerformLayout();
    }

    public Info Info
    {
       get;
       set;
    }

    protected override OnLayout(LayoutEventArgs e)
    {
        if(this.Info==null)
        {
            this.Size= Size.Empty;
            return;
        }

        Control control= this.Info.Control;
        this.Size= control.Size;           

        this.Controls.Add(control);
    }
}

有谁请让我知道，为什么第一次没有渲染添加的控件？

此致