How can I create checkable items in a QTreeWidget?

---

Answer:

In order to create checkable items in a QTreeWidget, you need to pass in the Qt::ItemIsUserCheckable flag to QTreeWidgetItem::setFlags in addition to calling QTreeWidgetItem::setCheckState(). See the following example for a demonstration:

#include <QApplication>
#include <QTreeWidget>

int main(int argc, char **argv)
{
    QApplication app(argc, argv);
    QTreeWidget box(0);
    box.setColumnCount(1);
    QTreeWidgetItem *itemOne = new QTreeWidgetItem(&box);

    itemOne->setFlags(itemOne->flags()|Qt::ItemIsUserCheckable);
    itemOne->setText(0,"Item one");
    itemOne->setCheckState(0, Qt::Checked);

    box.show();
    return app.exec();    
}