Hi Tiziano,

At first look, I cannot see anything that is obviously wrong with
this overlay. Could I ask you to send me a smaller one with nothing
in it but the problem lines? That might make diagnosis a bit simpler.

No relevant changes have occurred in the overlay format, by the way.
I did add some rather strange things to allow for "full-color" (RGB)
overlays, instead of restricting things to just 13 colors... but I
don't think that's a factor here. I may be able to comment more
intelligently once I see a smaller version with just the problem
lines; it'll cut down on my level of confusion.

Thanks! -- Bill