Maybe I'm missing something obvious here... but it seems that if I send a text message to someone, and then leave the window with the threaded conversation with that person open, when they reply the blue LED light does not go on like it usually does when an SMS comes in. I keep missing people's messages because of this!

It's not helped by the fact that it doesn't make the usual 'SMS recieved' sound either - just a little click which is really easy to miss.

Is there any way of changing this?

I was wondering this myself when I first purchased my N900, but according to other forum members, it would appear that this is by design.

I wish there was an option to turn on or off this feature, but it appears that it's up to Nokia to do so.

Maybe someone will figure a way to change this in the future.

It should only be doing this, if the screen is on. If you leave the conversation window open and the screen either times out or you lock the device, regular notification should happen.

I'm not 100 percent sure but I think it does this even when the screen has timed out.