Panel Image

Hello, what is the image of the main Gnome panel by default? I removed my panels and now, trying to get them back, that image is no longer there.

If you don't know what I'm talking about, you can find out by right-clicking the panel, selecting Properties, clicking the Background tab and seeing what the file is called that is chosen for "Background image" (which should be selected by default).

If you tell me what it is called I can find it myself on the system, otherwise if you know where it is exactly that would be great to know too :)

Thanks!