Flip phone face down mute call. Is there anyway to change the light threshold?

[twilk]

I flip the phone over and unless the screen is completly covered it doesnt work. If the screen is blacked out it works perfectly. But it takes a second or so to mute.

So basicly can I make the light threshold more sensitive.
Also it would be great to speed up the mute option. Possibly mute it automaticly.

Thanks, agian guys.