QWindow::showFullScreen() crashes the application

[rockinJ]

the code is simple.

    if(!window) {
        window = new QWindow;
        connect(window, SIGNAL(visibleChanged(bool)), this, SLOT(update(bool)));
        store = new QBackingStore(window);
    }
    window->showFullScreen();

this is inside a slot that is connected to a button click. When run to the line window->showFullScreen(), I got a segment fault and crashed.
Debugger shows:

1    QWindow::setWindowState  qwindow.cpp      1153
2    QWindow::showFullScreen  qwindow.cpp      1910
3    Widget::process          widget.cpp       73
...

on Windows 7, kit: Desktop QT 5.7.0 MinGW 32 bit
Any ideas? Please help. Thanks in advance!

[raven-worx]

@rockinJ
why do you need to create a QWindow by yourself?!
Are you sure about what you are doing?

[rockinJ]

@raven-worx
I want to create another window to show pictures in full screen besides my main window.

[mrjj]

@rockinJ said:

if(!window) {
    window = new QWindow;
    connect(window, SIGNAL(visibleChanged(bool)), this, SLOT(update(bool)));
    store = new QBackingStore(window);
}
window->showFullScreen();

do you set window pointer to NULL to start with?
else first time you click, u will crash at
window->showFullScreen();

[rockinJ]

@mrjj
Thank you! You solved the problem. Forgot to set window to null in constructor. Sorry, new to C++.

[mrjj]

@rockinJ
Hurra :)
well its a classic.

if you are using C++11 you are allowed to set directly in class

class XX {
QWindow *win=NULL;
};

[raven-worx]

@rockinJ
i was asking, because it's possible show any QWidget as window.
This is in most cases easier to handle, because most of the stuff then happens internally.

[rockinJ]

@raven-worx
I see, thanks anyway!