The xps program displays in an X Window the Unix processes
as a tree or forest, the roots of the tree are on the
left-hand side and the leaf processes (with no children)
are on the right-hand side.
The status of each process (running, sleeping, stopped,
etc.) can be indicated by a color. Different users can
appear as different colors too.
Within each level, processes are grouped so that those with
the same parent process id are grouped together. Within
this, processes are arranged by userid with lower number
uids appearing towards the top. In general, the order of
children is the order in which they were spawned, with the
older processes appearing towards towards the top.
In contrast to pstree and many tree-widget based programs,
the overall tree display uses diagonal lines; some effort
is made to effectively use the full 2-dimensional area of
the screen by balancing levels and centering the children
of a node between their parent. A goal of the program is to
visually give a picture of what's going on. So when
possible, processes are kept close to their parents so one
needn't scroll around too much and so that there isn't a
lot of redrawing as processes are created or destroyed.