[ferret_users] polygon is not filled correctly with pyferret

[Martin Schmidt <martin.schmidt@xxxxxxxxxxxxxxxxx>]

Hallo,
the following works well with ferret 6.9.51 (and earlier). It does not 
work with pyferret 6.96 (python 2.7)

Make a plot sst vs time.

yes? use coads_climatology
yes? set region/x=0/y=0
yes? plot/vlimit=20:30 sst

For an overlay define a rectangle on the plot. This is only an example.

yes? can region ! This is needed, since xp and yp seem to use an 
abstract x-axis
yes? let t0 = t[gt=sst,t=15-feb-0000]
yes? let t1 = t[gt=sst,t=15-may-0000]

yes? let xp = {`t0`,`t1`,`t1`,`t0`,`t0`}
yes? let yp = {21,   21,  29,  29,    21}

Draw a polygon, this works well
yes? polygon/nolab/over/line/col=8 xp,yp

Draw the same, but filled.
yes? polygon/nolab/over/fill/pal=grey xp,yp

With pyferret the rectangle is not filled correctly. I looks like a bug. 
I have found this with more complex data,
especially without a modulo time axis. can axis /modulo 
`sst,return=taxis` does not help!

Greetings,
Martin