Event filter with mouse events

[felo188]

Hi everyone.
Firstly sorry for my english.

I have some problem with qt so i decidied to ask You for help.

I'writting a program. I want to do somethink like this:
- when i move mouse on button, for example, should show table with data like name.
The main difficult to me is that the button is on MainWindow and if i want to show new table when the mouse is on button i must create new class or somethink like this.

I rode a lot about QMouseEvent and event filter but i stuck i don't know what i should do next.

1. Firts way i used event filter. Some code:.cpp

bool MainWindow::eventFilter(QObject *object, QEvent *ev)
{
    if (object == pushButton)
    {
        if(ev->type() == QEvent::Enter)
        {
            QApplication::setOverrideCursor( QCursor(Qt::CrossCursor) );
            return true;
        }
            else
            {
                return false;
            }
    }
    else
    {
        QApplication::restoreOverrideCursor();
        return false;
    }
}
...
...
MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    pushButton->installEventFilter(this);
}

bool MainWindow::eventFilter(QObject *object, QEvent *ev)
{
    if (object == pushButton)
    {
        if(ev->type() == QEvent::Enter)
        {
            QApplication::setOverrideCursor( QCursor(Qt::CrossCursor) );
            return true;
        }
            else
            {
                return false;
            }
    }
    else
    {
        QApplication::restoreOverrideCursor();
        return false;
    }
}
...
...
MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    pushButton->installEventFilter(this);
}

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I set a type of cursor because i wanted to see it is working.
.h

...
protected:
    bool eventFilter(QObject *object, QEvent *ev);
...

...
protected:
    bool eventFilter(QObject *object, QEvent *ev);
...

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This method isn't working. When I press Run button the application crash.

2.The second way is use EnterEvent and LeaveEvent. For that i create a new .h file and called him FlatButton when i declared:
.h

...
protected:
    void enterEvent(QEvent *ev);
    void leaveEvent(QEvent *ev);
...

...
protected:
    void enterEvent(QEvent *ev);
    void leaveEvent(QEvent *ev);
...

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In cpp file:

...
void FlatButton::enterEvent(QEvent *ev)
{
    QApplication::setOverrideCursor( QCursor(Qt::CrossCursor) );
}
void FlatButton::leaveEvent(QEvent *ev)
{
    QApplication::restoreOverrideCursor();
}
...

...
void FlatButton::enterEvent(QEvent *ev)
{
    QApplication::setOverrideCursor( QCursor(Qt::CrossCursor) );
}
void FlatButton::leaveEvent(QEvent *ev)
{
    QApplication::restoreOverrideCursor();
}
...

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When i replace FlatButton:: on MainWindow:: it's working but the cursor change type when enter or live MainWindow but i want to change him only on button. For this reason i created FlatButton.

I don't know where i do wrong. I would be grateful for help.