Bug in ioncore.goto_next() ?

Hello.

For testing I created a WTiling looking like 

  AABBCC
  AABBCC
  AABBDD
  AABBDD

In defbindings("WScreen" .. I created a binding for

kpress(PREFIX.."F", "ioncore.goto_next(_chld, <DIR>)",
"_chld:non-nil"),

Movement was like the following table where i think that "next"
is quite odd.

<DIR> - movement
right - A -> B -> D -> A
left  - A -> D -> B -> A
next  - A -> B -> D -> A
prev  - A -> D -> C -> B -> A

Bug, feature or nothing of the kind?

Jan J