On a Windows system,
if Galaxy rendering is enabled when Celestia starts,
then, if you do a "Capture Image" (menu item select or F10)
then the area covered by the file browser menu (or any other window)
is much brighter than the rest of the snapshot.
If you turn Galaxy Rendering off and then back on again without exiting from Celestia, the problem goes away. Subsequent snapshots do not show a bright area.
I just tested this with 1.3.0 pre6, pre5, 1.2.5 and 1.2.4. They all do it.
I first noticed it recurring when taking a picture of the nebula transparency bug reported elsewhere. At that point I was still using Detonator 40.72. I then upgraded to the current v43.45. They both do it.
This is a link to a larger image, where the problem is quite evident.
System:
256MB 500MHz Pentium3, Windows XP Pro, SP1
128MB Nvidia GeForce4 Ti4200, Detonator 43.45, OpenGL v1.4.0,
display running at 1600x1200, 85Hz, full color (32bits).