#include <QtWidgets>

class Test : public QMainWindow
{
    Q_OBJECT
public:
    Test() {
        QWidget *central = new QWidget();

        mTreeView = new QTreeView();
        mTreeView->setDragDropMode(QTreeView::DragDrop);
        mTreeView->setDefaultDropAction(Qt::MoveAction);
        mTreeView->setSelectionBehavior(QTreeView::SelectRows);

        QGridLayout *gridLayout = new QGridLayout(central);

        QStandardItemModel *model = new QStandardItemModel(2, 2);
        for (int row = 0; row < 2; ++row) {
            for (int column = 0; column < 2; ++column) {
                QStandardItem *item = new QStandardItem(QString("r %0, c %1").arg(row).arg(column));
                model->setItem(row, column, item);
            }
        }
        mTreeView->setModel(model);

        mHideColumn = new QPushButton("Hide");
        mShowColumn = new QPushButton("Show");

        connect(mHideColumn, SIGNAL(clicked()),
                this, SLOT(hideColumn()));
        connect(mShowColumn, SIGNAL(clicked()),
                this, SLOT(showColumn()));

        gridLayout->addWidget(mTreeView);
        gridLayout->addWidget(mHideColumn);
        gridLayout->addWidget(mShowColumn);

        setCentralWidget(central);
    }

    ~Test() {
        delete mTreeView->model();
    }

public slots:
    void hideColumn() {
        mTreeView->hideColumn(1);
    }

    void showColumn() {
        mTreeView->showColumn(1);
        mTreeView->resizeColumnToContents(0);
        mTreeView->resizeColumnToContents(1);
    }
private:
    QTreeView *mTreeView;
    QPushButton *mHideColumn;
    QPushButton *mShowColumn;
};

int main (int argc, char *argv[])
{
    QApplication a(argc, argv);
    Test test;
    test.resize(400, 400);
    test.show();
    return a.exec();
}

#include "main.moc"