Question 

 Solution

I tried using dexter in sourceinsight, but don't get the options in the preference menu as below.

How can I find the event handler option?

Check SourceInsight version : click Help > About Source Insight .. 
You must use even higher verion { 3.50.0072 }

• Source Insight download site :  http://www.sourceinsight.com/down35.html
• Download SiSetup.exe (about 5 MB). Save to an empty directory on your machine.