Hello Ansgar!

Replying to a message of Ansgar Konermann to All:

 AK> Hi All!

 AK> I recently started creating programs for the OS/2 Presentation Manager
 AK> using IBM's Visual Age C++. The DOCs mention "object
windows" to be a
 AK> special class of object, which can be used by applications.

 AK> What are these object windows good for?

Object windows are windows that only receive the WM_CREATE and WM_DESTROY
system messages. Any further messages received by the window have to be
sent by you.

PM applications should respond to any messages sent to them within 1/10-th
of a second. This is because the app could lock the system queue, there
where keyboard and mouse messages are queued before the app gets the
messages.

But object windows don't get keyboard/mouse or any other system messages,
thus they don't block the system queue; having said that, you can conclude
that the 1/10 rule does not apply to object windows. That is why object
windows are used in secondary threads, to perform operations that require
longer than 1/10-th of a second to complete.
By the way there is no use in having an object window in thread 1, as it
will block the thread for more than 1/10th sec, it still violates the
1/10th-rule (the messages are not removed from the input queues).

Bye, Erik!
[TeamOS/2 NL]
preferred personal reactions through e-mail
[internet: ErikH{at}hcc-gron.idn.nl]

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