[horde] How to follow code execution when sending email

[Mike Poznecki]

Hi, how in the world can I follow the execution path when sending an email?  I see code in compose-dimp.js, dimpcore.js, Compose.php and in Part.php.  I cannot understand why there are so many files involved. And I'm not sure if this is all the files that actually get executed.  Is there any type of map I can take a look at?
Thanks...Mike