systray[3/4]: Better validate icon owner

[Robert Shearman]

Reece Dunn wrote:
> On 06/02/2008, Robert Shearman <rob at codeweavers.com> wrote:
>   
>> PostMessage should correctly
>> handle the case where icon->owner has been destroyed and adding a call
>> to IsWindow just introduces a race condition.
>>     
>
> Is there a test case in the PostMessage tests to verify that behaviour?
>   

No - I don't think the tests will tell us anything we don't already 
know, but don't let me stop you adding a test for 
"PostMessage((HWND)0xdeadbeef, WM_USER, 0, 0)".

-- 
Rob Shearman