Closing new nonchild window in Qt

Question

Hello, i'm trying to make 2 windows. 2nd should be called in 1st. I don't connect them child->parent. But when i called 2nd window and closed it 1st window closed too. What should i do? Both windows are inhereted from QWidget. C++ and Qt

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Sorry for my poor describe. I have a main window. Class inherited from QMainWindow. That i created 2nd window. Class inherited from QWidget. In first (main window) i'm creating and calling 2nd window

ConfigWindow *ConfWindow = new ConfigWindow();
ConfWindow->show();

Without giving link to parent. Everything works fine, but when i close 2nd window (config-window) my main window is closing too. I needn't in this. What should i do to block closing main window after config-window closing.

Hope describe a little better.

My first window has this flags:

this->setWindowFlags(Qt::Tool | Qt::FramelessWindowHint);

Without them everything is fine. Could i change something if i need that flags in my window?

Answer 1

If this is the code, then there is a huge bug in Qt.
The code above should never close your first Windows, there must be something else wrong.
Is the application closed or does it crash?

Remark
Who is deleting configWindow? There is a Qt::WA_DeleteOnClose attribute that deletes the window after it is closed.

ConfigWindow *confWindow = new configWindow();
configWindow->setAttribute(Qt::WA_DeleteOnClose, true);
confWindow->show();

Answer 2

You need something like:

QApplication app(argc, argv);
app.setQuitOnLastWindowClosed(false);

Here is the test program: http://pastebin.com/f5903c5f4.

Beware, now you need to explicitly call quit() in the destructor of your main window.

If you read QApplication::quitOnLastWindowClosed documentation, you will find out that:

If this property is true, the applications quits when the last visible primary window (i.e. window with no parent) with the Qt::WA_QuitOnClose attribute set is closed. By default this attribute is set for all widgets except for sub-windows

Because your main window is a (frameless) tool window, it does count. That leaves ConfWindow as the only non sub-windows top-level widget. Thus, if you close ConfWindow, it provokes the application instance to quit.