winapi - 为什么是 HSHELL_WINDOWDESTROYED、HSHELL_WINDOWCREATED？

Question

MSDN - “ShellProc功能”，“RegisterShellHookWindow功能”：

 HSHELL_WINDOWCREATED   => A top-level, unowned window has been created.
 HSHELL_WINDOWDESTROYED => A top-level, unowned window is about to be destroyed.

但：

当仅对任何顶级无主窗口（带有任务栏按钮）执行 Hide/Show （或 set/cancel ）时，我们也会得到HSHELL_WINDOWDESTROYED/ 。为什么？任务栏按钮不是“真正的”窗口，不是吗？HSHELL_WINDOWCREATEDWS_EX_TOOLWINDOW

这个问题主要针对MS内部人员。