Why the synchronization bad doesnt't extend to other swinlanes?

Question

Why the syncronization bar does not go to other swinlantes when the for happens across lanes?

For example:

@startuml

|#Azure|L1|

start

:a10;

fork
  :a11;
fork again
  |#CornflowerBlue|L2|
  :a20;
fork again
  :a30;
fork again
  :a40;
endfork
|L1|
:a12;

end

@enduml

As it can be seen here:

http://plantuml.com:80/plantuml/png/gr5sh2ejIgtnCQpXuYekIImguUAoIZGqiERYIiilokPIK03o3At178N4zCJCFA1GZR9pVb5UMav-UMgHKqufKBTH3LYbaG6QIgj4OqmX4w1GQbuAs7omnK0hZ80M0iMu0000

or in another example:

@startuml

|#Azure|L1|
start
:a10;
fork
  :a11;
fork again
  |#CornflowerBlue|L2|
  :a20;
fork again
  |#Gold|L3|
  :a30;
endfork
|L1|
:a12;

end

@enduml

http://plantuml.com:80/plantuml/png/gr5sh2ejIgtnCQpXAYv9B2hXiaeqDB3cIiilokPIK01o324SXSJqnCmye52DidD-KLvQJdvvQf5JJYbGgr4DMAMH0OPAz_oSb1eVOuYyCL0-DIy5R3BOFg3XHjPS834k0000

Answer 1

posted 6 years ago, but problem is not solved (((