Vim Supertab like completion for a QCompleter

QtSupertab.cpp

//Somewhere when you create your completer
completer->popup()->installEventFilter(this);

bool CommandWidget::eventFilter(QObject *obj, QEvent *event) {
    if (obj == completer->popup()) {
        if (event->type() == QEvent::KeyPress) {
            QKeyEvent *keyEvent = static_cast<QKeyEvent*>(event);
            if (keyEvent->key() == Qt::Key_Tab) {
                //Select the next item in the completion list when tab is pressed - Supertab style
                QModelIndex index = completer->popup()->currentIndex();
                QModelIndex newIndex;

                if (index.row() == -1) {
                    //Nothing's selected - select the first entry
                    newIndex = completer->popup()->model()->index(0, 0);
                } else {
                    //Something's already selected - select the next one
                    //Going off the end of the list will automatically deselect everything
                    newIndex = completer->popup()->model()->index(index.row() + 1, index.column());
                }

                completer->popup()->setCurrentIndex(newIndex);

                return true;
            }
        }
    }

    //Pass the event on to the parent class
    return QWidget::eventFilter(obj, event);
}