How to force capital letters in input field?

[falconium]

I have created a subclass of QComboBox where I want to catch keys from 'a' to 'z' and manually force them to capital letters 'A'-'Z'. It has to be done real-time like caps lock was pressed.

I'm trying the following approach w/o success:

void CommandBox::keyPressEvent(QKeyEvent *e) {
    if (e->key() == Qt::Key_Return || e->key() == Qt::Key_Enter) {
        emit enterPressed(currentText());
    } else if (e->key() >= Qt::Key_A && e->key() <= Qt::Key_Z) {
        if (capital) e->setModifiers(Qt::ShiftModifier);
    }
    qDebug() << e->key() << e->modifiers();
    QComboBox::keyPressEvent(e);
}

void CommandBox::keyPressEvent(QKeyEvent *e) {
    if (e->key() == Qt::Key_Return || e->key() == Qt::Key_Enter) {
        emit enterPressed(currentText());
    } else if (e->key() >= Qt::Key_A && e->key() <= Qt::Key_Z) {
        if (capital) e->setModifiers(Qt::ShiftModifier);
    }
    qDebug() << e->key() << e->modifiers();
    QComboBox::keyPressEvent(e);
}

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The modifier is set, I can see it in the printout of qDebug(), but the character is still lower case in the field.
Any guess?

Thanks!