Re: [win32gui] [perl-win32-gui-hackers] [Fwd: RE: alarm() doesn't work on Windows 2003 and Windows Vista]

[Robert M. <rm...@po...>]

Glenn,

Do you have a pointer to the whole thread so that I can have a browse.

Thanks,
Rob.

Glenn Linderman wrote:
> for swap stack trickery sounds bad... and I doubt we are doing it in 
> Win32::GUI...  Thought I'd put it here for the record, if nothing else.
> 
> -------- Original Message --------
> To: jand@ActiveState.com
> Message-Id: <200...@ll...>
> Date: Fri, 09 Dec 2005 20:29:41 +0000
> From: Nick Ing-Simmons <ni...@in...>
> 
> Jan Dubois <jand@ActiveState.com> writes:
> 
>> On Fri, 09 Dec 2005, Nick Ing-Simmons wrote:
>>
>>> Jan Dubois <jand@ActiveState.com> writes:
>>> >Yes, both the original code, and the patch switching from NULL to 
>>> (HWND)-1
>>> >were from you.
>>>
>>> I have no memory of the (HWND)-1 change at all :-(
>>> Can you point me at the perforce change where I did it ?
>>
>>
>> http://public.activestate.com/cgi-bin/perlbrowse?patch=14160
> 
> 
> Hmm, well it was obviously me. I can only assume I had been reading MSDN
> help on PeekMessage() and saw the use mentioned.
> It does look like a speculative change.
> 
>>
>>> I assume that the change to (HWND)-1 was to avoid grabbing events
>>> destined for GUI. If that is really a problem then I suppose WM_TIMER
>>> events should be posted to a real (invisible?) window created for that
>>> purpose.
>>
>>
>> Yes, that would be a possibility, but I would want to avoid the 
>> additional
>> complexity if it is not needed.  I'll check it out if this would solve 
>> the
>> issue on Windows 2003. Maybe it is trivial to do this.
>>
>> I do sometimes worry about additional message pumps dispatching GUI 
>> messages
>> at "arbitrary" times during Perl execution, but I haven't found any real
>> issues yet.  I think a problem would happen if you execute a Perl 
>> callback
>> in response to a message, and while you are still in the callback, 
>> another
>> message triggers a different callback.  Couldn't the first callback mess
>> with the stack(s) of the second callback?
> 
> 
> They can and they do. Which is why Tk does some swap-stack trickery
> (thanks to Sarathy telling me how).
> 
>>
>> However, this happens all the time in GUI applications with modal
>> dialog boxes.  
> 
> 
> Quite, so GUI apps have to cope - what is less clear is what happens
> to perl code (or core) that does not know there is a GUI.
> 
>> Another area is COM synchronization, which also happens
>> through the message queue (using hidden top level windows for
>> non-GUI programs).  Every COM method call or property access will spin
>> the message pump and deliver GUI messages to windows too.
>>
>> Cheers,
>> -Jan
> 
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