Problem with Sidebar and Screensaver

I wasn't using the Sidebar for a while, and recently started, now that there
are some useful Outlook widgets to use. However, when Sidebar is running,
when the Photos screensaver kicks in, it drops my (hi-res) screen resolution
down to 1024x768 or so. This is really annoying, because then all my windows
have been scrunched up to fit. If Sidebar isn't displayed, the Photos
screensaver leaves the screen resolution alone. Any ideas? I haven't seen any
screen resolution options in the screensaver, of course.