The main part of the display shows 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.  Which processes shown
is determined various settings. Once can select all processes, or a
specific process owned by specific users, and possibly kernel 
processes as well.

Process status (running, sleeping, stopped, etc.) of shown processes
is indicated by a color.

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 uid's appearing towards the top.

This means root processes always appear at the extreme top, assuming
the processes' parent was also a root process.  Finally, among
processes that have a common parent (or no parent) and belong to the
same userid, those with lower process numbers appear 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.

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.  But since a goal of the program is to visually
give a picture of what's going on, when possible processes are kept
close to their parents so one needn't scroll around too much and so
that doesn't there isn't a lot of redrawing as processes are created
or destroyed.

One can click on a process to get more information (via C<ps>) about
that process, send a signal to the process, or set its priority
(assuming you have the permission to do so).

The majority of processes in a system, one hopes, are sleeping
processes.  The color to be selected for uid's of sleeping process can
be specified by X resources.  If however a color is not specified, one
is chosen at random. Generally, all processes belonging to a given
user will be a unique color. For certain terminal programs like
C<xterm> or C<telnet>, the name if the user is displayed rather than
the program name.

