Force dialog to have WhatsThis title bar button

I would like a dialog to display the "?" whats this button in the title bar. This is a Windows app and I am currently running Windows 7 on my dev machine. I have tried

MyDialog::MyDialog(QWidget* parent)
: QDialog(parent, Qt::WindowTitleHint | Qt::WindowSystemMenuHint | Qt::WindowMaximizeButtonHint | Qt::WindowContextHelpButtonHint)

but the "?" button does not appear. I know that this is OS dependent and that the WindowFlags are hints and not commands and I suspect that this button not appearing has something to do with the OS (version?). But there has to be a way to force it to appear so that users have a visible way to go into What This mode. How is this done?

QDialog, by default has the Context Help button (or WhatIsThis), do not set any flags, it will appear.

If you are looking for Context Help button and Maximize button to co-exist then that is not possible, Windows does not support it.

Refer Here

Thanks that helped. I keep forgetting the the window hints behave differently on different OS/Windowing systems. IE. with X11 you can have min/max buttons along with the What's This button in the title bar but not on Windows.