Is it possible to hide a polyline in MapPoint? I tried to do this by setting both the Fill and the Line visible properties to false, but a thin polyline remains visible.
Thanks for any help.

No, you cannot hide a polyline. You will always see the thin line. The reason for this is probably something to do with the fact that "marquee" selection isn't available in MapPoint's basic drawing toolset - so if you could hide a line it would be very hard to select again for editing or deletion.