QStyle::drawControl and QStyle::CE_DockWidgetTitle

When drawing a titlebar by passing in the Qt::Tool flag to the titleBarFlags of QStyleOptionTitleBar as shown in the example below, then the titlebar does not look like the titlebar of a tool window.

void Wid1::paintEvent(QPaintEvent *)
{

QStyleOptionTitleBar o;
o.init(this);
o.text = "Title";
o.titleBarFlags = Qt::Tool;
QPainter painter(this);
style()->drawComplexControl(QStyle::CC_TitleBar, &o, &painter, this);
}