Graphical Artifacts / Glitches since 5.1.0 on Windows

[nitrog42]

Hi everybody, we have a small problem with our app since we upgraded to Qt 5.1.0 (from 5.0.2)
Here it is :

!http://www.filesdnd.fr/up/Bug.png(Glitch)!

The main layout is a GridLayout, and we're just adding a widget as first element :
QPair<unsigned, unsigned> currentPosition = positions.at(0);

    if (_lastBonjourState == BONJOUR_SERVICE_OK)
    {
        if (!_infoWidget)
        {
            _infoWidget = new CenterInfoWidget(this);
        }
        _infoWidget->setNoDeviceMode();
        ui->gridLayout->addWidget(_infoWidget, currentPosition.first, currentPosition.second);
    }

Do you have any idea on what could cause this ? I didn't find any similar problem on the bug tracker or the forum, we're a bit lost about that...

[JKSH]

What did it look like in Qt 5.0.2?

If you didn't find a bug report, you can file one (attach your Qt 5.0.2 and Qt 5.1 screenshots)

[ChrisW67]

bq. Do you have any idea on what could cause this ?

Cause what? You need to tell what you perceive as the problem.

[nitrog42]

Sorry, i didn't realize it might not be obvious !
Here a normal screen :
http://filesdnd.fr/promo/forum4.png (no display because it break the forum !)
In the first screen, you can see graphical artefact (the green round corner is duplicated, line drawed without reason).

The code hasn't been modified, I just upgraded Qt and with the 5.1 version we have that problem, in debug and release.
It disappears if a move the windows (probably because of a redraw), but it come back.