MSDN - "ShellProc Function", "RegisterShellHookWindow Function":
HSHELL_WINDOWCREATED => A top-level, unowned window has been created.
HSHELL_WINDOWDESTROYED => A top-level, unowned window is about to be destroyed.
But:
we'll get HSHELL_WINDOWDESTROYED/HSHELL_WINDOWCREATED also when only do Hide/Show (or set/cancel WS_EX_TOOLWINDOW) to any top-level unowned window (with taskbar button).
Why? Taskbar button isn't "true" window, isn't it?
This question primarily for MS insiders here.