Thanks for the always accurate information and the examples. I guess
the only one who could clarify is Adam.
As you can also see from your image, I can't understand why it comes
to the case where the background is completely covered by black. It's
definitely my fault, but I don't feel like seeing such a behavior of
the plugin, and I wouldn't know how to explain it in the manual. In
this case I agree with IgorBeg who says to hide it, and with Andrew-R
to let the memory remain on the Bug Tracker for future developments.
(OT: I would like to try again to convince you to attend the CinGG
mailing-list too; your knowledge would be fundamental...)