Sequence Diagram: Exclude messages from loop

Question

What I'm trying to achieve can be seen in this SO-Answer: https://stackoverflow.com/a/51236207/1955344

Please note the loop on the right. It groups the messages of the right outer most lane, but does not wrap around the message which is coming from the adjacent left lane, although this message is pointing in the loop.

Is this possible? I tried it, but it seems impossible to me, due to the on/off nature of groups.

I marked this question with the category "Question/help". If it is a feature that does not exist yet, please feel free to change the category to "Wanted feature".

Comments

Hello A.,

It is not yet possible with PlantUML.
It is more a wanted feature, but:

From SO-51191521:

Here is an attempt with PlantUML (using sub-diagram):

@startuml
mainframe sd h_e
label l1 [
{{
[o-> O2  : do_t()
activate O2
O2 -> O1 : m_b()
activate O1
O1 -> O1 : do_w()
activate O1
deactivate O1
O1 ->>] : signal() \t\t
O1 -> O1 : do_m()
activate O1
deactivate O1
O2 <-- O1
deactivate O1
deactivate O2
}}
]
label l2 [
{{
|||
|||
T o<-] : m_a()
activate T
loop
T -> T : w()
activate T
deactivate T

|||
[->> T : \t\t\t
T -> T : h_s()
activate T
deactivate T

T -> T : do_o()
activate T
deactivate T
deactivate T
end
}}
]
@enduml

If that can help,
Regards,
Th.