在第二个表单上插入选项卡页时出现异常

Question

我的主窗体启动一个辅助窗体，其中包含一个所有者绘制的选项卡控件。然后，主窗体调用辅助窗体中的公共函数，以在给定索引处插入选项卡页。我一直在我的 tabcontrol 的 DrawItem 事件处理程序中遇到此异常：

System.ArgumentOutOfRangeException: 'InvalidArgument=Value of '2' is not valid for 'index'.
Parameter name: index'

在此代码中：

private void tabControl_DrawItem(object sender, DrawItemEventArgs e)
{
     TabPage thisTab = tabControl.TabPages[e.Index];
...

相关的调用堆栈是：

    System.Windows.Forms.dll!System.Windows.Forms.TabControl.GetTabPage(int index)  Unknown
    System.Windows.Forms.dll!System.Windows.Forms.TabControl.TabPageCollection.this[int].get(int index) Unknown
>   tabControl_DrawItem(object sender, System.Windows.Forms.DrawItemEventArgs e) Line 751   C#
    System.Windows.Forms.dll!System.Windows.Forms.TabControl.OnDrawItem(System.Windows.Forms.DrawItemEventArgs e)   Unknown
    System.Windows.Forms.dll!System.Windows.Forms.TabControl.WmReflectDrawItem(ref System.Windows.Forms.Message m)  Unknown
    System.Windows.Forms.dll!System.Windows.Forms.TabControl.WndProc(ref System.Windows.Forms.Message m)    Unknown
    System.Windows.Forms.dll!System.Windows.Forms.Control.ControlNativeWindow.OnMessage(ref System.Windows.Forms.Message m) Unknown
    System.Windows.Forms.dll!System.Windows.Forms.Control.ControlNativeWindow.WndProc(ref System.Windows.Forms.Message m)   Unknown
    System.Windows.Forms.dll!System.Windows.Forms.NativeWindow.DebuggableCallback(System.IntPtr hWnd, int msg, System.IntPtr wparam, System.IntPtr lparam)  Unknown
    [Native to Managed Transition]  
    [Managed to Native Transition]  
    System.Windows.Forms.dll!System.Windows.Forms.Control.SendMessage(int msg, System.IntPtr wparam, System.IntPtr lparam)  Unknown
    System.Windows.Forms.dll!System.Windows.Forms.Control.ReflectMessageInternal(System.IntPtr hWnd, ref System.Windows.Forms.Message m)    Unknown
    System.Windows.Forms.dll!System.Windows.Forms.Control.WmOwnerDraw(ref System.Windows.Forms.Message m)   Unknown
    System.Windows.Forms.dll!System.Windows.Forms.Control.WmDrawItem(ref System.Windows.Forms.Message m)    Unknown
    System.Windows.Forms.dll!System.Windows.Forms.Control.WndProc(ref System.Windows.Forms.Message m)   Unknown
    System.Windows.Forms.dll!System.Windows.Forms.ScrollableControl.WndProc(ref System.Windows.Forms.Message m) Unknown
    System.Windows.Forms.dll!System.Windows.Forms.Control.ControlNativeWindow.OnMessage(ref System.Windows.Forms.Message m) Unknown
    System.Windows.Forms.dll!System.Windows.Forms.Control.ControlNativeWindow.WndProc(ref System.Windows.Forms.Message m)   Unknown
    System.Windows.Forms.dll!System.Windows.Forms.NativeWindow.DebuggableCallback(System.IntPtr hWnd, int msg, System.IntPtr wparam, System.IntPtr lparam)  Unknown
    [Native to Managed Transition]  
    [Managed to Native Transition]  
    System.Windows.Forms.dll!System.Windows.Forms.NativeWindow.DefWndProc(ref System.Windows.Forms.Message m)   Unknown
    System.Windows.Forms.dll!System.Windows.Forms.Control.DefWndProc(ref System.Windows.Forms.Message m)    Unknown
    System.Windows.Forms.dll!System.Windows.Forms.Control.WndProc(ref System.Windows.Forms.Message m)   Unknown
    System.Windows.Forms.dll!System.Windows.Forms.TabControl.WndProc(ref System.Windows.Forms.Message m)    Unknown
    System.Windows.Forms.dll!System.Windows.Forms.Control.ControlNativeWindow.OnMessage(ref System.Windows.Forms.Message m) Unknown
    System.Windows.Forms.dll!System.Windows.Forms.Control.ControlNativeWindow.WndProc(ref System.Windows.Forms.Message m)   Unknown
    System.Windows.Forms.dll!System.Windows.Forms.NativeWindow.DebuggableCallback(System.IntPtr hWnd, int msg, System.IntPtr wparam, System.IntPtr lparam)  Unknown
    [Native to Managed Transition]  
    [Managed to Native Transition]  
    System.Windows.Forms.dll!System.Windows.Forms.NativeWindow.DefWndProc(ref System.Windows.Forms.Message m)   Unknown
    System.Windows.Forms.dll!System.Windows.Forms.Control.DefWndProc(ref System.Windows.Forms.Message m)    Unknown
    System.Windows.Forms.dll!System.Windows.Forms.Control.WndProc(ref System.Windows.Forms.Message m)   Unknown
    System.Windows.Forms.dll!System.Windows.Forms.TabControl.WndProc(ref System.Windows.Forms.Message m)    Unknown
    System.Windows.Forms.dll!System.Windows.Forms.Control.ControlNativeWindow.OnMessage(ref System.Windows.Forms.Message m) Unknown
    System.Windows.Forms.dll!System.Windows.Forms.Control.ControlNativeWindow.WndProc(ref System.Windows.Forms.Message m)   Unknown
    System.Windows.Forms.dll!System.Windows.Forms.NativeWindow.DebuggableCallback(System.IntPtr hWnd, int msg, System.IntPtr wparam, System.IntPtr lparam)  Unknown
    [Native to Managed Transition]  
    [Managed to Native Transition]  
    System.Windows.Forms.dll!System.Windows.Forms.TabControl.InsertItem(int index, System.Windows.Forms.TabPage tabPage)    Unknown
    System.Windows.Forms.dll!System.Windows.Forms.TabControl.TabPageCollection.Insert(int index, System.Windows.Forms.TabPage tabPage)  Unknown

在由主表单调用的第二个表单中的公共例程中，我插入在选项卡控件的index=1处新建一个选项卡页，选项卡控件默认以两个选项卡开始。发生此异常时，选项卡控件的 TabPages 成员只有两个默认选项卡页，而我在已经创建了第三个选项卡页的公共函数的调用堆栈中（位于index=1) 通过 TabPages.Insert(,) 例程。

当我将辅助窗体更改为非对话框时（这意味着我从父窗体调用 Show() 而不是 ShowDialog()），这种情况开始发生，这样两种窗体都可以同时进行互动。我尝试在更改选项卡页面之前将焦点添加到第二个表单，但这没有帮助。