#include <QtGui>

class MainWindow : public QWidget
{
    Q_OBJECT
public:
    MainWindow(QWidget *parent = 0)
        : QWidget(parent)
    {
        lineEdit = new QLineEdit;

        QCheckBox *checkBox = new QCheckBox("Predictive Enabled");
        checkBox->setChecked(true);
        checkBox->setFocusPolicy(Qt::NoFocus);
        connect(checkBox, SIGNAL(toggled(bool)), this, SLOT(enablePredictive(bool)));

        QBoxLayout *layout = new QVBoxLayout;
        layout->addWidget(lineEdit);
        layout->addWidget(checkBox);
        setLayout(layout);
    }


public slots:
    void enablePredictive(bool enable)
    {
        if (enable) {
            lineEdit->setInputMethodHints(lineEdit->inputMethodHints() & ~Qt::ImhNoPredictiveText);
        } else {
            lineEdit->setInputMethodHints(lineEdit->inputMethodHints() | Qt::ImhNoPredictiveText);
        }
    }

private:
    QLineEdit *lineEdit;
};

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

    MainWindow window;
    window.showMaximized();

    return app.exec();
}

#include "main.moc"