problems with proportional plots



Dear list,

in my work as a teacher I often use the packages draw and qdraw for 
drawing plots for my students. Sometimes I want to draw proportional 
plots (this means that a circle is a circle on the screen and not an 
ellipse). Some months ago I succeeded in making such plots with qdraw by 
editing the file wgnuplot.ini, where I set the option "GraphSize=800 
800". But this is only a provisional solution. Now I found on the 
website of Mario Riotorto the following setting:

     "set_draw_defaults( grid=true,  proportional_axes=xy)"$

After this setting, when I do

     wxdraw2d(region(x^2+y^2<1 ,x,-1.5,1.5,y,-1.5,1.5))

I get a circle in the wxMaxima-window. But when I dow

     draw2d(region(x^2+y^2<1 ,x,-1.5,1.5,y,-1.5,1.5));

I get an ellipse in the gnuplot-window. When I do

     qdraw(ex(x^2,x,-3,3),more(proportional_axes=xy));

I also get a non-proportional plot in the gnuplot-window.

If I don't make the setting proportional_axes=xy, I get proportional 
plots with draw and qdraw (due to my GraphSize-setting), but 
non-proportional plots with wxdraw2d. I cannot fix this problem because 
I don't know the connections between maxima, gnuplot, draw and so on. I 
guess that it has to do with my change of the GraphSize option, but I 
don't remember the original setting. How can I fix this problem (and if 
possible understand the reason).

I use wxMaxima 0.8.6 in Windows XP.

Thanks for any help,
Christian