[Qt-interest] Error with QtMainWindow

[Michael Müller]

Hello out there,

we have a strange problem concerning Qt 4.4.2- running on Windows XP, 
SP3. The strange thing about it is that it runs fine under Ubuntu. Ok, 
the problem:
In my code i do that:

    widget = new QtMainWindowControl(parent, this, flags);
    // we have to enable visibility to get a proper layout (see bug #1654)
    widget->setVisible(true);

Where QtMainWindowControl is a subclass of QtMainWindow. Everything 
compiles fine, but setVisible(true) causes an exception. The problem is 
that i can just debug until

ShowWindow(q->internalWinId(), sm);

in qwidget_win.cpp. I cant step into this Win API function. When i skip 
this function the exception is thrown in

inline QObject *parent() const { return d_ptr->parent; }

because d_ptr is NULL. Unfortunately, i have no Debug information 
anymore at that point. Someone has an idea what i`ve forgot and why this 
works on Linux, but not on Windows?

Regards
Michael Müller