branching with self-message in sequence diagram

[Assink]

Hi,

I like to use "branch with previous message" on a self-message (call of another method on the same object)  which follows a message to another object. Why is this option not available in the context-menu?

By the way, what's the difference between the Self-Message and the Recursion element in the toolbox? They seem to have the same effect. I have the same question with respect to the Message and Call element.

Greetings,

Herman Assink