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Wireshark-dev: [Wireshark-dev] Should Qt SimpleDialog messages be posted to event queue?

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From: Tomasz Moń <desowin@xxxxxxxxx>
Date: Wed, 1 May 2019 12:23:16 +0200
Hello,

While investigating the "extcap terminates without connecting to
pipes" issue [1], I have noticed that the "interrupt-like" behavior is
induced by the simple_dialog() call. The simple_dialog() calls exec()
on QMessageBox which in turn executes the events from the message
queue. See [2] for better explaination.

One approach to solve the problem of "unwanted interruptions" would be
to change simple_dialog() function to post user-defined event to the
event queue. This would avoid the problem by limiting the number of
places where the events from the event queue can be handled. In
opinion such change impacts the overall user interface architecture.

If simple_dialog() gets changed to post user-defined event, then the
code that calls simple_dialog() will continue to execute before the
message box gets displayed to the user. This can be surprising to some
developers, but in my opinion it is much easier to handle such
asynchronous message box behavior, than to handle the possible
"interrupt-like" executions of different actions while another action
executes. The message box can still be modal (blocking until the user
closes it) in this approach.

What do you think about changing simple_dialog() to be asynchronous?
Is there some better approach?

Best Regards,
Tomasz Moń

[1] https://bugs.wireshark.org/bugzilla/show_bug.cgi?id=15743
[2] https://bugs.wireshark.org/bugzilla/show_bug.cgi?id=15743#c2