Axis Modified in Exported Image: Bug or Feature?

Hi all,

a friend discovered something I don't know if it's a bug or feature:
make test=p
display test
ModifyGraph minor(bottom)=1
ModifyGraph margin=28, width=340.157,height=141.732

saves the graph as displayed. Everything is fine up to now.

Let's change the size a little and save again...
ModifyGraph width=283.465,height=141.732

the displayed axis should be similar but it differs from the saved image.

Using manually computed ticks
ModifyGraph manTick(bottom)={0,20,0,0},manMinor(bottom)={10,5}

the result is as expected.

Altering the axis according to the available space is a good thing, but why is it different for the displayed and the saved graph (since the dimensions are fixed in this case)?
Occasionally, a graph can be right on the edge between one setting and another. The conditions can be just slightly different when rendering at high resolution to move to the other side.

Note that if you use an 8X expand rather than 600dpi, there is no difference.

To test, I used PNG export to the clip and load into the picture gallery.

Larry Hutchinson
For some combinations it also appears on the "8X" export (my friend used this option in the first place, with several waves and a lot of offsets).

So the answer is: the axes get re-rendered during the save process and if it's a close call manually computed ticks should be used.
Maybe this could get documented somewhere in the manual?