Possible rendering bug at 16-bit depth

Hi.

I recently installed gqview onto my Ubuntu linux system, and found a
strange rendering bug which affects images with smooth gradients. As I
thought the bug was related to the XFCE desktop, I logged the bug at:
http://bugzilla.xfce.org/show_bug.cgi?id=922

Since then, I've also installed a straight Debian Testing (Sarge)
system, and I thought I'd try to reproduce the same problem using the
Gnome desktop. As the same problem exists, I'm begining to think that
the bug is more in gqview (or, of course, something that it depends on)
rather than in XFCE.

I could log all the bug details in another bug-tracking system, but for
the moment, I'm assuming that xfce's bugzilla is the best place for it. 

There's a screenshot at:
http://bugzilla.xfce.org/attachment.cgi?id=216
(ignore the backdrop at the top, the window in the bottom left is
epiphany, the window at the bottom right is gqview). I should also
explain that I'm always obliged to run my xservers (either XFree or
xorg) in 16-bit depth (24 bit hasn't worked for years).

Unfortunately, I'm not a developer, so I don't know where to go next.
Does anyone here have any ideas?

Many thanks, Jaime




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