You can have a bool store it in some file (some custom made settings file for your application) or use the QSettings [doc.qt.nokia.com] class to store it (and any other settings for application)

QErrorMessage [doc.trolltech.com] might be what you want, although the “dont’t show again” info is not saved permanently (by means of QSettings).

I’ve decided to go with my own custom dialog box, but is there an easy and/or standard way of displaying the default system message box icons for warning/information/error ?

You can use QStyle::standardIcon() [doc.trolltech.com]

with one of these values for the StandardPixmap standardIcon parameter:

Perfect!

BTW – it’s always worth to have a look into the sources of Qt itself, that’s the place where I found this :-)

To save the settings you could have a look at QSettings [doc.qt.nokia.com] for platform-independent application settings.