Andres, So far I have been told by two AT developers that using
WM_GETOBJECT is how to do it.  I guess there is no downside to them
though :-)  The downside is to app users not using AT but experiencing a
performance degradation, however minor.  Have you collected any data on
the occurrence of these false positives to know how rare or non-rare
they are?

An AT present flag would be helpful.  Please start a new thread on this
list for that.

Thanks, Pete
===
Andres Gonzalez wrote:
> WM_GETOBJECT is NOT a reliable way of detecting AT either, since it
> may be triggered by apps and even device drivers that don't have
> anything to do with AT, so you are guarantied false positives even
> with the best heuristics. I'm very interested in developing a reliable
> handshake mechanism with AT, and would love to hear from others with
> ideas/proposals on this respect. Perhaps we can take this task for the
> next edition of IA2 in this list, or by a subgroup of interested
> parties, and bring back a concrete proposal to the general group.
>  
> Thanks,
>  
> --Andres.
>  
>  
>
>     ------------------------------------------------------------------------
>     *From:* [email protected]
>     [mailto:[email protected]] *On
>     Behalf Of *Pete Brunet
>     *Sent:* Monday, May 24, 2010 4:18 PM
>     *To:* James Teh
>     *Cc:* IAccessible2 mailing list
>     *Subject:* Re: [Accessibility-ia2] screen reader present flag
>
>     Thanks Jamie, I'll have to check with the architects to see if
>     they would have any issues with blocking.  If I can block then I
>     might also be able to lazily call into the secondary thread to
>     build the tree as needed.  -Pete
>     ===
>     James Teh wrote:
>>     On 25/05/2010 8:37 AM, Pete Brunet wrote:
>>       
>>>     Thanks Jamie, [using WM_GETOBJECT to dynamically enable accessibility] 
>>> may be a problem for the case where the app has
>>>     multiple threads and a secondary thread needs to be called by the window
>>>     proc to participate in the building of the accessibility tree.  Is it
>>>     acceptable to block the UI thread?
>>>         
>>     I don't see why this is any different to creating the tree in the same 
>>     thread. Either way, it will block the UI thread, as the WM_GETOBJECT 
>>     message needs to return the requested accessible object. Can you shorten 
>>     the setup time by creating parts of the tree lazily only when requested?
>>
>>     Jamie
>>
>>           
>
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