API ajax doesn't handle json properly

Chaining API is making an ajax interface way faster (cuts the requests). Hovever, GET or POST don't handle natively super well multi-dimensional objects (eg api.sub.action = array (xxx)

I fixed/improved the civicrm/api/Json that works with json params (in POST)
entity=event,
action=getsingle
params={"name":"test event","api.participant.create":{"contact_id":42,"role_id":1}}"

So params is a string containing a json encoded param, that can be as complex as wanted

X+