#include <QApplication>
#include <QWidget>
#include <QPainter>
#include <QStyleOptionViewItem>

class MyWidget: public QWidget
{
public:
    MyWidget(QWidget* parent)
        : QWidget(parent)
    {
    }

    void paintEvent(QPaintEvent * event) override
    {
        Q_UNUSED(event);

        QPainter painter(this);

        QStyleOptionViewItem option;
        option.initFrom(this);
        option.rect = rect();
        option.text = "Selected text";
        option.widget = this;
        option.state |= QStyle::State_Selected;

        style()->drawPrimitive(QStyle::PE_PanelItemViewItem, &option, &painter, this);
    }
};

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);

    MyWidget w(nullptr);
    w.show();

    return a.exec();
}