[Qt-interest] return to command line but the GUI is still alive

[william.crocker at analog.com]

>> What bothers me now is that this issue is still not mentioned in the
>> Qt documentation (as determined by a grep for the word: "fork".)
>
> That's because the documentation is not exhaustive about every single possible 
> use of Qt, with all the permutations of non-Qt functions available.
>
> The reason I pointed out the fork issue is because of the problem we had in 
> KDE three weeks ago. If we hadn't run into that problem, I wouldn't have 
> learned what I learnt.
>
> In any case, we don't want to document undefined behaviour. We want to leave it 
> undefined so that, in the future, things may change.

My problem was 2+ years ago. That makes this the future
and this issue has not changed. I recommend one sentence
in the documentation for:

    void QProcess::setupChildProcess()

which states the following:

    Warning: We do not recommend the use of any Qt classes or functions
       from a forked (Unix) context as they may require acquisition of a 
Mutex
       which is currently held by another (now frozen) thread.

You could also point out that (in general, with Qt) there is no such
thing as a single threaded application because even if the user does
not run multiple threads, Qt does or may.

Bill