Qt 4.8 + QWebkit -> white rendering of widgets when mouse hovers

[devarde]

In my company the Q.A. has Win8 and when it tests my application done in Qt4.8 with QWebkit occurs a strange effect:
After the application startup when the user clicks with the mouse over a widget, it becomes white. After that every widget hovered by the mouse becomes white too including the own program window. The behavior of program is not affected, but it becomes impossible to use the program because absolutely all is rendered white.

when this problem is triggered other applications are not affected.

Googling about the problem the unique article that is closer what is happening to me is located on http://www.qtcentre.org/threads/64431-App-becoming-white-when-running-on-Windows-without-Qt-installed.

Does anyone have any suggestion?

Thanks