Octave uses gnuplot for graphics rendering. Since a few month, producing dashed lines doesn't work. I found that this requires the termoption "dashed" to be set.
The gnuplot interface of Octave tries to work correctly with older versions, in order to use only supported features. In the present case, can "set termoption dashed" be used in 4.2.5 and 4.4?
As test here, "set termoption dashed" works in 4.4.0 but not in 4.2.5.