BalloonGrobText spacing

[Noeck]

Hi,

I tried to use the BalloonGrobText. I know that it is still experimental.

I tried the following code and I expected that \balloonLengthOff means
notes and other stuff does not wait for the text to be finished. In
other words: the text should not influence the positioning of the rest.
1st question: Am I right? Is that how it is meant to be?

This snippet shows that this only works sometimes (for the first key
signature for example) but not always (not for the key signature change).
2nd question: Why not?
3rd question: What can I do to achieve this?

\version "2.17.9"

\new Staff \with { \consists "Balloon_engraver"}
{
  \relative c'' {
    \balloonLengthOff
    \balloonGrobText #'KeySignature #'(1 . -3) "Here it works"
    \key g \major
    a1 a1
    \balloonGrobText #'KeySignature #'(1 . -2) "Here it doesn't"
    \key f \major
    a1
  }
}

Any help is apreciated!
Joram