[ferret_users] testcase--Weird behavior for centered palette over a FRAME gif grab

[Pierre St-Laurent <p_st_laurent@xxxxxxxxxxxxxxxx>]

Dear Ferret users,

Here is probably the shortest code that reproduces the bug :

\cancel mode journal
use etopo120
repeat/l = 1 ( \
  set viewport left; \
  shade rose; \
  set viewport right; \
  shade/pal=centered rose; \
  frame/file=pal_frame.gif;\
)

Just run it first in batch mode (ferret -gif), then comment the lines

frame/file=pal_frame.gif;\
repeat/l = 1 ( \
)

and run in standard mode (ferret). Compare the result with the
pal_frame.gif figure. Colors around 0 are different (in fact colors are
wrong in the .gif file).

The bug only occurs within viewport and that's why Ansley M. couldn't
reproduce the bug in simple tests.

I hope it will be easy to correct.

Pierre