Cross Java program -- screen shot.
The image shows two crossing line segments.
The segment which slants down to the right has been
selected by the user. The perpendicular segment,
which slants up to the right, has been calculated
by the program. The intersection is marked by a
small filled circle overlaid with a slightly larger `X'.
At the bottom are two numeric fields which show the angles
of the segments in degrees, relative to the horizontal.