QGraphicsView selection problem when there is large scale factor in view (Linux)

[MadBear]

Greetings,
I would like to show QGraphicsScene. The scene bounding rectangle is (0,0,1,1). The problem is that then the selection of items on linux doesn't work correctly. On Windows there are no problems.
To better explain this I have created simple application with QGraphicsView of dimensions (500,500) in a simple QMainWindow:

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    scena=new QGraphicsScene();
    ui->graphicsView->setScene(scena);
    ui->graphicsView->scale(500,500);
    QGraphicsEllipseItem *it=new QGraphicsEllipseItem();
    it->setRect(-0.1,-0.1,0.2,0.2);
    it->setFlags(QGraphicsItem::ItemIsMovable | QGraphicsItem::ItemIsSelectable);
    scena->addItem(it);
}

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    scena=new QGraphicsScene();
    ui->graphicsView->setScene(scena);
    ui->graphicsView->scale(500,500);
    QGraphicsEllipseItem *it=new QGraphicsEllipseItem();
    it->setRect(-0.1,-0.1,0.2,0.2);
    it->setFlags(QGraphicsItem::ItemIsMovable | QGraphicsItem::ItemIsSelectable);
    scena->addItem(it);
}

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Is there some bug in linux version of qt? I have qt 4.7.

Thank you,
MadBear

[HelderC]

I tried this code, and works fine:

QGraphicsScene *scena = new QGraphicsScene();
    ui->graphicsView->setScene(scena);
    ui->graphicsView->scale(500,500);
    QGraphicsEllipseItem *it=new QGraphicsEllipseItem();
    it->setRect(-0.1,-0.1,0.2,0.2);
    it->setFlags(QGraphicsItem::ItemIsMovable | QGraphicsItem::ItemIsSelectable);
    scena->addItem(it);

QGraphicsScene *scena = new QGraphicsScene();
    ui->graphicsView->setScene(scena);
    ui->graphicsView->scale(500,500);
    QGraphicsEllipseItem *it=new QGraphicsEllipseItem();
    it->setRect(-0.1,-0.1,0.2,0.2);
    it->setFlags(QGraphicsItem::ItemIsMovable | QGraphicsItem::ItemIsSelectable);
    scena->addItem(it);

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