Key Press Events are ignored in listview in a mdisubwindow or Dock widget on 64bit cocoa when any one of the Japanese input sources are used.

(add to pro file : )
CONFIG -= x86
CONFIG += x86_64

(main.cpp)

#include <QtGui>

class MyWidget: public QWidget
{
    Q_OBJECT
    
public:
    MyWidget(QWidget *parent = 0);

protected:
    bool event ( QEvent * event );
    
private:
    QHBoxLayout *layout;
    QListWidget *lw;
};        

class MyListWidget: public QListWidget
{
    Q_OBJECT
    
public:
    MyListWidget(QWidget *parent = 0) : QListWidget(parent){};

protected:
    bool event ( QEvent * event );
    
};        

bool MyListWidget::event ( QEvent * event )
{
    if (event->type() == QEvent::KeyPress)
    {
        qDebug() << "== Key Press@MyListWidget";
    }
    else if (event->type() == QEvent::KeyRelease)
    {
        qDebug() << "== Key Release@MyListWidget";

    }
    return QListWidget::event(event);
}

MyWidget::MyWidget(QWidget *parent) : QWidget(parent) 
{
    setWindowTitle("Support Tester");
    layout = new QHBoxLayout;
    lw = new MyListWidget; // changed create object from QListWidget to MyListWidget by sra
    layout->addWidget(lw);

    QStringList list;
    list << "1" << "2" << "3" << "4" << "5" << "6";

    lw->addItems(list);

    setLayout(layout);
    
}

bool MyWidget::event ( QEvent * event )
{
    if (event->type() == QEvent::KeyPress)
    {
        qDebug() << "Key Press@MyWidget";
    }
    else if (event->type() == QEvent::KeyRelease)
    {
        qDebug() << "Key Release@MyWidget";

    }
    return QWidget::event(event);
}

//This moc include is to get everything in a single file - for quick testing only
#include "main.moc"

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    MyWidget *myWin = new MyWidget();
//    myWin->show();      //this works as expected.
//    myWin->raise();


    MyWidget *myWin2 = new MyWidget();
    QMdiArea *mdi = new QMdiArea();

    mdi->addSubWindow(myWin2);

    mdi->show();

    return app.exec();
}