plotting points



Using wxmaxima 0,7.1 with maxima 5.12.0
i get different results, plotting points, than in previous versions.

As an example, take the function
f(x):=3*x
and define the lists:

xl:create_list(x,x,[-1,0,1,2])
yl:create_list(f(x),x,[-1,0,1,2])

then try to plot points:

  plot2d([discrete,xl,yl],[gnuplot_curve_styles,["with points pointtype 5 
pointsize 1"]])

or 

wxplot2d([discrete,xl,yl],[gnuplot_curve_styles,["with points pointtype 5 
pointsize 1"]])

I get a continuos plot in ranges [x,-1,2], [y,-3,6]


Using maxima 5.10, without wxmaxima, i get a plot with points, as expected. 

What has changed?

thank you 

Pol