No stencil buffer - no shadows

A question about klepto's miniB3D module.

In both Graphics3D() & CanvasGraphics3D() functions you check whether there are stencilBits. If not you print the "No stencil buffer - no shadows" message.
What does it mean?

I didn't get the message with Graphics3D() but now I use CanvasGraphics3D() and I get this message every flip-cycle (because I use both 2D and 3D graphics).
That's very annoying during development. It's of course easy for me to remove these messages, but you didn't put them for nothing, did you?

This means that you won't be able to use shadows or any stencil operations with his module as your card does not support "windowed stencil", only fullscreen.

Do you use anything that casts shadows or the like?

N, I don't use cast shadows. Thanks for the answer.