Only let one instance of the application run

I need to figure out how to get just one instance of my application to run. Currently
there can be more than one instance running on the same machine. Under the windows
API I would just say if(!hPrevInstance) in WInMain. Does anyone know how its done in QT

Thanks,
chrisdsimpson

This subject has been discussed several times. Please search the forums for "QtSingleApplication".