Created attachment 72470 [details]
sample code of the test case

Created attachment 72471 [details]
crash backtrace of the test case

Also you can use this use case: Is the same of the kdelibs/kdeui/test but this time we add more items after the view has been setup, please also note the comments about setCategorizedModel; so here is *another use case*:

-- CUT FROM HERE ---


    #include <QMainWindow>
    #include <QStringListModel>
     
    #include <kapplication.h>
    #include <kaboutdata.h>
    #include <kcmdlineargs.h>
    #include <kiconloader.h>
     
    #include <kcategorizedview.h>
    #include <kcategorydrawer.h>
    #include <kcategorizedsortfilterproxymodel.h>
     
    QStringList icons;
     
    class MyModel
        : public QStringListModel
    {
    public:
        virtual QVariant data(const QModelIndex &index, int role) const
        {
            switch (role) {
                case KCategorizedSortFilterProxyModel::CategoryDisplayRole: {
                        return QString::number(index.row() / 10);
                    }
                case KCategorizedSortFilterProxyModel::CategorySortRole: {
                        return index.row() / 10;
                    }
                case Qt::DecorationRole:
                    return DesktopIcon(icons[index.row() % 4], KIconLoader::Desktop);
                default:
                    break;
            }
            return QStringListModel::data(index, role);
        }
    };
     
    int main(int argc, char **argv)
    {
        icons << "konqueror";
        icons << "okular";
        icons << "plasma";
        icons << "system-file-manager";
     
        KAboutData aboutData("KCategorizedViewTest",
                             0,
                             ki18n("KCategorizedViewTest"),
                             "1.0",
                             ki18n("KCategorizedViewTest"),
                             KAboutData::License_LGPL_V3,
                             ki18n("(c) 2009 Rafael Fernández López"),
                             ki18n("KCategorizedViewTest"),
                             "http://www.kde.org");
     
        KCmdLineArgs::init(argc, argv, &aboutData);
        KApplication app;
     
        QMainWindow *mainWindow = new QMainWindow();
        mainWindow->setMinimumSize(640, 480);
        KCategorizedView *listView = new KCategorizedView();
        listView->setCategoryDrawer(new KCategoryDrawer());
        listView->setViewMode(QListView::IconMode);
        MyModel *model = new MyModel();
     
        model->insertRows(0, 100);
        for (int i = 0; i < 100; ++i)
        {
            model->setData(model->index(i, 0), QString::number(i), Qt::DisplayRole);
        }
     
        KCategorizedSortFilterProxyModel *proxyModel = new KCategorizedSortFilterProxyModel();
        proxyModel->setCategorizedModel(true);
        proxyModel->setSourceModel(model);
     
        listView->setModel(proxyModel);
     
        //NOTE if you disable temporally the CategorizedModel flag work ok but the scroll bar fails
        //proxyModel->setCategorizedModel(false);
     
        //BEGIN HERE
        model->insertRows(0, 100);
        for (int i = 0; i < 100; ++i)
        {
            QModelIndex mi = model->index(0,0);
            model->setData(model->index(i, 0, mi), QString::number(i), Qt::DisplayRole);
        }
        //END HERE
       
        //NOTE if you reenabled the flag works fien but the scroll bar fails
        //proxyModel->setCategorizedModel(true);
     
       
        mainWindow->setCentralWidget(listView);
     
        mainWindow->show();
     
        return app.exec();
    }

--- UNTIL HERE ---

Gave it a short test:
case KCategorizedSortFilterProxyModel::CategorySortRole seems never be queried and the proxymodel most likely runs into a race on the items (ie. with i<2 everything is fine since there're only two non equal items and so is if you pass QString::number(index.role()) as display role.

Don't ask me why, i got the nature of the bug wrong and then looked out of curiosity. I've never touched or seen the kcat'model code. Sorry.

Hi,

kdelibs (version 4 and earlier) is no longer maintained since a few years.

KDE Frameworks 5 or 6 might already have resolved this bug.

If not, please re-open against the matching framework if feasible or against the application that shows the issue.

We then can still dispatch it to the right Bugzilla product or component.

Greetings
Christoph Cullmann