draw background color of WOverview

[Be-ing]

Previously setting the BgColor element of an Overview element in the skin XML did nothing.

[daschuer]

I think we can than remove the not working:

    QPalette palette; //Qt4 update according to http://doc.trolltech.com/4.4/qwidget-qt3.html#setBackgroundColor (this could probably be cleaner maybe?)
    palette.setColor(this->backgroundRole(), m_qColorBackground);
    setPalette(palette);

[daschuer]

Thank you, LGTM.