QCompleter and a UnionModel query internal submodels

Hi,
I am trying to create a lineedit with a completer that queries different models based on the length of the lineedit's input. In the test example below, the completer should match against one model if the input has a length less or equal three characters. with 4-6 charachters, the completer should match against the other model and with more characters match against both. It doesn not work however :(. If I modify the code to start out in UnionModel::MatchAll mode and change onTextChanged to return immediately without applying changes to the match mode the completer can match against both models, so I think the code works to some extent, thus it may be some QCompleter internals that keep this from working ...
Can anybody tell me what I am doing wrong?

Code:

#include <QtGui>
 
class Model : public QAbstractListModel
{
    Q_OBJECT
public:
    Model(QStringList& list, QObject* parent = 0)
            : QAbstractListModel(parent), m_list(list) {}
 
    int rowCount(const QModelIndex& parent = QModelIndex()) const {
        return m_list.count();
    }
 
    QVariant data(const QModelIndex& index, int role = Qt::DisplayRole) const {
        if (!index.isValid()) return QVariant();
        if (role == Qt::DisplayRole) {
            return m_list.at(index.row());
        }
        return QVariant();
    }
 
private:
    QStringList m_list;
};
 
class UnionModel : public QAbstractListModel
{
    Q_OBJECT
    Q_PROPERTY(MatchMode matchMode READ matchMode WRITE setMatchMode)
public:
    UnionModel(QObject* parent = 0)
            : QAbstractListModel(parent),
            m_matchMode(UnionModel::MatchInput) {
        m_applicationModel = new Model(QStringList() << "oneoneoneone" << "twotwotwotwo", this);
        m_inputModel = new Model(QStringList() << "oneoneone" << "twotwotwo", this);
    }
 
    enum MatchMode { MatchApplications, MatchInput, MatchAll };
 
    int rowCount(const QModelIndex& parent = QModelIndex()) const {
        Q_UNUSED(parent)
        switch (m_matchMode) {
            case UnionModel::MatchInput:
                return m_inputModel->rowCount();
            case UnionModel::MatchApplications:
                return m_applicationModel->rowCount();
            case UnionModel::MatchAll:
                return (m_inputModel->rowCount() + m_applicationModel->rowCount());
        }
        return 0;
    }
 
    QVariant data(const QModelIndex& index, int role = Qt::DisplayRole) const {
        if (!index.isValid())
            return QVariant();
 
        if (role == Qt::DisplayRole) {
            if (m_matchMode == MatchInput) {
                return m_inputModel->data(index);
            }
 
            else if (m_matchMode == MatchApplications) {
                return m_applicationModel->data(index);
            }
 
            if (index.row() < m_inputModel->rowCount()) {
                return m_inputModel->data(index);
            }
 
            QModelIndex idx = m_applicationModel->index(qAbs(index.row() - m_inputModel->rowCount()));
            return m_applicationModel->data(idx);
        }
 
        return QVariant();
    }
    MatchMode matchMode() const {
        return m_matchMode;
    }
 
public slots:
    void setMatchMode(UnionModel::MatchMode mode) {
        if (m_matchMode != mode) {
            m_matchMode = mode;
            emit matchModeChanged(mode);
        }
    }
 
private:
    MatchMode m_matchMode;
    Model* m_applicationModel;
    Model* m_inputModel;
 
signals:
    void matchModeChanged(UnionModel::MatchMode mode);
};
 
class LineEdit : public QLineEdit
{
    Q_OBJECT
public:
    LineEdit(QWidget* parent = 0) : QLineEdit(parent) {
        QCompleter* c = new QCompleter(this);
        UnionModel* model = new UnionModel(c);
        c->setModel(model);
        c->setCompletionRole(Qt::DisplayRole);
        setCompleter(c);
        QObject::connect(this, SIGNAL(changeModeRequest(UnionModel::MatchMode)),
                         model, SLOT(setMatchMode(UnionModel::MatchMode)));
 
        connect(this, SIGNAL(textChanged(const QString&)),
                this, SLOT(onTextChanged(const QString&)));
    }
private slots:
    void onTextChanged(const QString& text) {
        if (text.trimmed().isEmpty()) return;
 
        UnionModel::MatchMode mode;
        int len = text.length();
 
        if (len < 3) {
            mode = UnionModel::MatchInput;
        }
 
        else if (len >= 3 && len <= 6) {
            mode = UnionModel::MatchApplications;
        }
 
        else {
            mode = UnionModel::MatchAll;
        }
 
        emit changeModeRequest(mode);
    }
signals:
    void changeModeRequest(UnionModel::MatchMode mode);
};
 
int main(int argc, char** argv)
{
    QApplication app(argc, argv);
    LineEdit le;
    le.show();
    return app.exec();
}
 
#include "main.moc"

p.s. Maybe I have to call a function to tell the view/completer etc. that the rowCount() has changed ...