Event filter with mouse events

[high_flyer]

Only crash MyProgramInQT.exe not a Windows.

The screenshot you posted says your window manager crashed, so either its not the message you get, or, as I said, your windows managers is crashing.

[felo188]

shows a Windows message box somethink like this

I mean message box only looking like this one. My message says that MyProgramInQT.exe stops working not a system Windows

[high_flyer]

I mean message box only looking like this one. My message says that MyProgramInQT.exe stops working not a system Windows

What is the point of not giving the exact information? do you want help or not?
Sending people on the wrong track will not help you!
Are you sure your project is in debug mode?
It sounds like you are starting a release mode project.
Make sure you are in debug mode, and start the debugger, it will then stop on the line that is crashing.
Post that line here, and then we can start seeing where the problem is.

[felo188]

Sorry for misleading.

When i click Start Debugging (F5) debug stops at this
The code from Compile Output:

Running build steps for project Mysz...
Configuration unchanged, skipping qmake step.
Starting: "E:\Programy\QtSDK\mingw\bin\mingw32-make.exe"
E:/Programy/QtSDK/mingw/bin/mingw32-make -f Makefile.Debug
mingw32-make[1]: Entering directory `C:/Users/Lukasz/Desktop/Mysz-build-desktop'
mingw32-make[1]: Nothing to be done for `first'.
mingw32-make[1]: Leaving directory `C:/Users/Lukasz/Desktop/Mysz-build-desktop'
The process "E:\Programy\QtSDK\mingw\bin\mingw32-make.exe" exited normally.

[high_flyer]

please stop post external links with screenshots.
Attach the screenshots to the post, since after some time the external links stop being valid, and the post loses information, which might be important for people reading this in later time.
Also, for posting a section of code you can simple cope the code and paste it here with [code] tags.

Where is 'pushButton' defined, and where do you initialize it?

[felo188]

It's a screenshot window.jpg.

I didn't have a defined pushButton so i added it:

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    QPushButton *pushButton = new QPushButton("button1",this);
    pushButton->installEventFilter(this);
}

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    QPushButton *pushButton = new QPushButton("button1",this);
    pushButton->installEventFilter(this);
}

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Now the program stops crashing.
I'm wondering why the event filter don't working.

bool MainWindow::eventFilter(QObject *object, QEvent *ev)
{
    if ((object == pushButton) && ev->type() == QEvent::Enter)
    {
        QApplication::setOverrideCursor(QCursor(Qt::CrossCursor));
        return true;
    }
    if ((object == pushButton) && ev->type() == QEvent::Leave)
    {
        QApplication::restoreOverrideCursor();
        return true;
    }
    else
        return false;
}

bool MainWindow::eventFilter(QObject *object, QEvent *ev)
{
    if ((object == pushButton) && ev->type() == QEvent::Enter)
    {
        QApplication::setOverrideCursor(QCursor(Qt::CrossCursor));
        return true;
    }
    if ((object == pushButton) && ev->type() == QEvent::Leave)
    {
        QApplication::restoreOverrideCursor();
        return true;
    }
    else
        return false;
}

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When the cursor is on button he should change a type to cross but he don't change.

[high_flyer]

I didn't have a defined pushButton so i added it:

Thats is not true.
If there was not a defined 'pushButton' you would have gotten a compile error.
Which is also the reason your event handler "is not working".
You have a defined a local 'pushButton' in your constructor, which is being initialized, but the 'pushButton' in your evnetFilter is declared somewhere else, probably in your header in class scope, but it is not initialized, hence it never matcher your if() statements.
It seems you have no idea how classes in C++ work, and what are members.
Hence, this is becoming off topic for this forum.

[felo188]

I solved my problem.
.h

...
QPushButton *pushButton;
....

...
QPushButton *pushButton;
....

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and .cpp

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    pushButton = new QPushButton("button1",this);
    pushButton->setGeometry(50,45,60,25);
    pushButton->installEventFilter(this);
}

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    pushButton = new QPushButton("button1",this);
    pushButton->setGeometry(50,45,60,25);
    pushButton->installEventFilter(this);
}

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high_flyer anyway thanks for help.