Message on Message for Sequence Diagram

[gnimor]

I am a little bit lost. I try to do something similar as it is shown in the sequence all in one example. I have attached an image what I want to achieve. In words: I want to have a message within (on top of) a message but I don't know the syntax for that or how to do it via drag and drop? It seems just changing the layout "to back" or "to top" doesn't help

[afdia]

Shouldn't this already be possible and shown in the sequence all in one palette? (upper right element)

[SSteve]

You can do that with multiple on statements:

obj=Lifeline A~a 
on=a
tick=
on=a
a->a +:self message
tick=

There are probably other ways to do it. I'm still trying to figure out sequence diagrams.