I've searched for an answer on this and the closest I can find is this discussion on the proximity sensor's delays: http://talk.maemo.org/showthread.php?t=67026

This is not what I'm looking for.

When I use my N900 indoors, the proximity sensor works fine.
However, if I use it outdoors in the daytime, when I take it away from my face to look at it to hang up, see if I have a signal, or even answer after pulling it out of my pocket, the display will either flash on then blank again, or simply won't come back from being blanked at all.
My only option for using the phone at this point is to open the keyboard (I have rotation enabled) as that overrides the sensor. Kind of awkward when trying to get on a train carrying a computer.

I tested the sensor (with proximityd) and found that in a dark room, it detects my thumb from about 20mm away... double the distance that I read it is supposed to sense.

Note that I live in South Florida... likely a tad brighter sun than many here are getting this time of year. I know the sensor is an IR emitter/detector pair, but that nuclear furnace puts out a tremendous amount of IR down here.

Hence my question: Does anyone know of a way to adjust the sensitivity of the proximity sensor?
I'd like to dial it back by about 70%.