Raining effect in 2d cockpit how to make it ?

Hi
i have see that some plane in fs2004 have raining effect in 2d cockpit !
i know how to make raining effect in the vc cockpit but in 2d cockpit ???
some body know how to implement the raining effect in the 2d cockpit
i have see that some plane in fs2004 have raining effect in 2d cockpit !
i know how to make raining effect in the vc cockpit but in 2d cockpit ???
some body know how to implement the raining effect in the 2d cockpit
