Grafik xrect

[Georg Fuss]

num = 1;
scf(num);
xselect();
clf(num);

a = gca();
a.isoview = "on";
a.data_bounds = [ -3 -3; 3 3 ];

plot( [-2 2], [0.5  0.5] );  //  i

xset("color",5);

xrect( -1, 1, 1, 1 ); // ii

xset( "color", 1 ); // iii

This little script does, what I expect.
A straight line is plottet (i). A square is plottet(ii).
Last not least the scaled axes a shown.

What I do not understand:
 Without the last statement I see rectangle very seldom.
Without the statment (i) I do not get the scaled axes.

Sorry, if that is a silly question