Yes, belMarduck. But what insearchof has described isn't trompe de l'oeil, is it?
Trompe de l'oeil has nothing behind it.
This jewelry box has a framed painting which is actually a framed painting. It's not trompe de l'oeil.
It's just that behind the framed painting, there is something inside. It happens to be a treasure. The framed picture provides a sort of protective coloration for what would otherwise appear on the wall as a vault -- a sure giveaway [of treasure, inside].
Actually, it is more than protective coloration "sort of". It is actually protective coloration. It is a painting which protects the jewelry in the box behind.
The essential thing about trompe de l'oeil, as I understand it, is that it fools the eye into thinking there is depth when there really isn't any depth.
In fact, if you look at a trompe de l'oeil painting from a different angle, the illusion disappears. As Anu explained in his AWAD a week ago Friday, the viewer is supposed to discover that the painting is a 'trick'. That's the whole point of it. On the other hand, the purchaser of insearchof's jewelry box will not think it is any fun if a stranger discovers her jewelry behind the painting. :)
That's why I compared trompe de l'oeil with a platitude [mouthed by a hypocrite*]. If you scratch the surface of a platitude, there is not a trace of it in the person who mouthed it.
* Oops! Never got around to posting the association with "hypocrite". But a truism in the mouth of a hypocrite is a platitude. In the mouth of someone who actually believes what they're saying, it's an aphorism. :)
P.S. to Capfka [re post below].
I did not understand belMarduk to say that insearchof's jewelry box with framed painting was "trompe de l'oeil". I understood her to say that the term "trompe de l'oeil" is relevant to what we are discussing here, if only as a contrast to what we are discussing here, which, of course, it is.
In any case, belMarduk will let us know for sure, I'm sure. :)