[PyQt] A dire warning message

Algis Kabaila akabaila at pcug.org.au
Thu Jul 7 13:00:28 BST 2011

On Thu, 7 Jul 2011 09:03:47 PM Hans-Peter Jansen wrote:
> Dear Al,
> On Thursday 07 July 2011, 11:22:34 Algis Kabaila wrote:
> > This bothersome warning message probably has nothing to do with PyQt.
> > However, it does occur whenever I use PyQt.  No great harm seems to
> > occur and the programs function normally, except for that message.
> > Is there something wrong with my setup or should I just forget all
> > about it?
> > 
> > I attach a little test program "open.py". It does not do anything -
> > and just tries to open a  file dialog after a click on the
> > pushButton.  That produces the error message.
> > 
> > The "program" is mainly filled with the message itself and some
> > comments. I would think that this probably has been dealt with, but I
> > will not know if I do not ask... so thanks again for your patience.
> > OTH, may be other people will find this informative, too - or am the
> > only one being subjected to this warning?
> > 
> > #!/usr/bin/env python3.2
> > '''
> > open.py - a sample program to show the dire warning it generates
> > and every other program that tries to use a file read dialog.
> > Platform - kubuntu 11.04 "natty"
> > Python 3.2
> > Qt 4.7.2 (from "natty" binaries.
> > PyQt4 4.8.4 - bound to Python 3.2 whilst compiling
> > 
> > On opening a file dialog, I get this warning:
> > 
> > KGlobal::locale::Warning your global KLocale is being recreated with
> > a valid main component instead of a fake component, this usually
> > means you tried to call i18n related functions before your main
> > component was created. You should not do that since it most likely
> > will not work
> > 
> > Search on the net seems to give some grim news:
> > 
> > <quote start>
> > Re: VLC Hangs on Open File dialog
> > Postby Rémi Denis-Courmont » Sat Jan 29, 2011 11:58 pm
> > In the mean time, someone in KDE actually looked at the issue.
> > It turns to be a longstanding known bug in the QProcess class from
> > Qt4. That bug gets triggered by a new "feature" in KDE 4.6 relative
> > to MIME types in the Open and Save dialogs, that happens to involve
> > the QProcess class.
> > 
> > In the end, VLC is blaming KDE, KDE is blaming Qt, and Qt is blaming
> > the kernel.
> > <quote end>
> > '''
> Hmm, at the first glance, this is a KDE problem, since KDE plugs its own
> file dialog into Qt, but fails to properly deal with locales there
> after due to them not being initialized correctly. This is going to
> produce issues, if you're calling QFileDialogs and expects them being
> localized correctly. It might be possible to circumvent these issues by
> instancing KApplication instead of QApplication (and doing the proper
> KDE4 setup sequence).
> Detlev is doing a nice trick in eric4: it checks, if PyKDE4 is
> available, and uses it, otherwise it uses plain Qt4.
> How this could be related to QProcess escapes me but what do I know..
> Pete

Yes, I recall Detlev putting me right on other issues with PyKDE4 - requires 
putting a tick on one of the configuration boxes of eric.  I am using eric5 
(that's the python3 version). I will install the newest version and look for 
the "box to tick" - Detlev is a very helpful guy!

The message does occur exactly the same way when the scripts are fired from 
CLI. I should try it on a gnome desktop in order to avoid PyKDE4.  IIRIC, 
PyKDE4 is not windows compatible.  And that is a problem if one wants to 
ensure compatibility with Windows - I do not really care about that. Too late 
for me  :).
Thanks, Pete,

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