[Interest] application appearance changing when laptop goes in saving energy mode

[Jason H]

I'd see what WM_* message(s) are being sent. Specifically WM_DISPLAYCHANGE, WM_FONTCHANGE, etc.

Qt is probably initializing correctly, then when WM_DISPLAYCHANGE happens, they get reset back to defaults, without picking up Qt's customizations. If you can identify the message, you can filter it out. 


> Sent: Wednesday, December 02, 2015 at 6:05 AM
> From: maitai <maitai at virtual-winds.org>
> To: Interest at qt-project.org
> Subject: Re: [Interest] application appearance changing when laptop goes in saving energy mode
>
> Hello,
> 
> Still searching to fix that one.
> 
> I can now reproduce it at leasure: If I connect my laptop to an external 
> monitor, launch the application, then unplug the external monitor and 
> hover the mouse on the windows bar to make it appear (autohide is 
> activated), my application AND QtCreator changes font, palette and 
> style.
> 
> Then only way to get normal look back is to restart application. 
> Reloading style, stylesheet, palette and font at application level does 
> not fix existing widgets once they are corrupted.
> 
> I cannot find what trigger this, nor at qApp's event level or at 
> QMainWindow level or at widget's level.
> 
> I am using qt 5.5.1 on windows 10. It does not seem to occur on Windows 
> 7 as far as I can tell.
> 
> I have users complaining about that too so it is not just me ;)
> 
> Any idea how to catch what is causing that and avoid it? Since it occurs 
> also in QtCreator maybe I should open a bug report...
> 
> Thanks
> Philippe Lelong
> 
> 
> Le 09-11-2015 16:45, maitai a écrit :
> > Thanks Robert for your reply,
> > 
> > In fact I succeeded to reproduce partly the problem. I have a laptop
> > with 2 graphic cards, switchable. Whenever the PC goes in power-saving
> > mode, it switches to the intel one. When this happens, my menubar
> > (regular QMenuBar) is changing font and becomes ugly, and the only way
> > to get it back to normal is to restart the application. It seems to
> > happen also from time to time if I switch from external monitor to
> > laptop monitor.
> > 
> > This app is not using opengl, it's just a plain QWidget app.
> > 
> > No signal or event as far as I can see is triggered when this happens,
> > just a paintEvent it seems.
> > 
> > The funny thing is that even QtCreator is impacted by that... It also
> > changes font or style.
> > 
> > Any clue on what is going on there?
> > 
> > Thanks
> > Philippe Lelong
> > 
> > Le 09-11-2015 12:03, Robert Iakobashvili a écrit :
> >> On Mon, Nov 9, 2015 at 7:54 AM, maitai <maitai at virtual-winds.org> 
> >> wrote:
> >>> 
> >>> Hello
> >>> 
> >>> On Windows, some users are reporting that the application style 
> >>> (font? palette?) is changing when laptop goes in energy saving mode, 
> >>> and becomes more or less unreadable (white font on white background, 
> >>> etc). I have seen that myself also a couple of times but I'm unable 
> >>> to reproduce it.
> >>> 
> >>> When it occurs, putting the laptop back on power does not fix 
> >>> anything, and the only way to get back the proper appearance is to 
> >>> restart the application. If you start the application when in battery 
> >>> saving mode, no problem. The application is widget-based 
> >>> (QMainWindow, QGraphicalScene, QMenubar, etc), Qt is 5.5.1 but that 
> >>> was reported also with previous Qt versions.
> >>> 
> >>> As I said this occurs only for a few users, and I cannot reproduce 
> >>> it. Maybe it's connected with the laptop changing GPU, I don't know.
> >>> 
> >>> Does anyone knows what could possibly trigger this, and if I can 
> >>> catch it somehow either to avoid it or reload style/palette/font/etc 
> >>> when it occurs?
> >>> 
> >>> Thanks
> >>> Philippe Lelong
> >> 
> >> 
> >> Hi,
> >> 
> >> With which options Qt was configured and built?
> >> 
> >> Any plugins your software is using?
> >> 
> >> Is it correlating with any particular Windows versions
> >> like on Windows-10 or 8.1?
> >> 
> >> That sounds like an aggressive memory optimization by OS.
> >> Locking in memory sometimes could help against.
> >> 
> >> There is a Qt signal
> >> 
> >> QGuiApplication::on_applicationStateChanged(Qt::ApplicationState 
> >> state);
> >> 
> >> and using it on Android.
> >> 
> >> Perhaps, coming to the state:Qt::ApplicationActive from
> >> somewhere else and reloading fonts, etc could be a work-around?
> >> 
> >> Kind regards,
> >> Robert
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