shell32/tests: Fix a test on Win2k platform and above.

[Nicolas Le Cam]

2009/3/18 Vincent Povirk <madewokherd+8cd9 at gmail.com>:
> On Tue, Mar 17, 2009 at 4:50 PM, Nicolas Le Cam <niko.lecam at gmail.com> wrote:
>> Tell me if you have a better solution.
>
> You should add some traces first to find out what window is getting
> this notification and when. The test data currently doesn't have
> enough information to decide on a correct fix.
>
> Vincent Povirk
>
>
>

On Win2k after the last SHAppBarMessage(ABM_REMOVE, &abd) call, a
ABN_POSCHANGED is sent to windows[2].hwnd, but at that time user data
has been set to null :

Remove first appbar
    * second appbar receives ABN_POSCHANGED notification
    * third appbar receives ABN_POSCHANGED notification
Remove second appbar
    * third appbar receives ABN_POSCHANGED notification
Remove third appbar
    * third appbar receives ABN_POSCHANGED notification

In short, it ignores the ABN_POSCHANGED notification with null user
data if it's the last appbar being removed that receives it.

The current patch only change the test's behaviour for this case, as
registered_count will only be null before the last
SHAppBarMessage(ABM_REMOVE, &abd) call (and before the first
SHAppBarMessage(ABM_NEW, &abd) call but at that time you can't get
notifications)

-- 
Nicolas Le Cam