I'm running gallery-screensaver 1.5.1-b17 under Windows, using jre1.5.0_12.
My machine has a dual-screen.
Whenever the screensaver becomes active, it displays images centered to the combined screen area of both screens, i. e. one half of the image on the right side of the left screen, and the other half of the image on the left side of the right screen.
I would prefer the image to be displayed on both screens (best), or only on the primary screen (2nd best.)