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?