<p>How would one go about capturing users keystrokes in the SMS composer on the Symbian OS, specifically for a Nokia N73 (or any of the symbian supported devices <a href="http://en.wikipedia.org/wiki/Symbian_OS#Devices_that_have_used_the_Symbian_OS" rel="nofollow noreferrer">http://en.wikipedia.org/wiki/Symbian_OS#Devices_that_have_used_the_Symbian_OS</a>)? I'm new to symbian development and I'm trying to write an application to analyse writing styles of those who send SMSs. Any information (or push in the right direction) would be great.</p>

<p>Many Thanks,</p>

<p>A</p>

Well, there are several levels to answering to your question.
The keystrokes are actually captured by the message editor application. So, either it provides an API to feed you all its keystrokes (you can look for one on
http://forum.nokia.com
. You'll find the message editor API but it will be mostly about re-using GUI controls and not what you're looking for) or you would need a transparent application of your own that stays in the foreground and captures keystrokes before feeding them back to whatever application happens to be right behind. Fortunately (for obvious security reasons), Symbian OS will not allow you to do the later.
You can, however, have your own application read messages when they are saved in the  phone memory: when they are saved in the Draft folder or in the SMS Outbox.
The obligatory shameless plug: I would advise reading the messaging chapter of
http://www.quickrecipesonsymbianos.com
in order to understand how to use the Symbian Message Store
The classes of interest in your case are : CmsvEntry, CMsvSession, MMsvSessionObserver, CMsvOperation and CSmsClientMtm.