The slide effect doesn't completely remove forced blur and background
contrast roles. According to EffectWindow::setData implementation,
void EffectWindowImpl::setData(int role, const QVariant &data) { if (!data.isNull()) dataMap[ role ] = data; else dataMap.remove(role); emit effects->windowDataChanged(this, role); }
in order to delete previously set data, we should pass a null variant.