Top is a windowed version of the console top command, which provides a dynamic real-time
view of a running system. It has only a small fraction of the options provided by its
console counterparts, but hopefully the most used ones.
Top supports the following features:
* easy sorting according to cpu/mem/user/command/...
* shows either all processes or only the processes matching a given user;
* select and kill processes appearing in the list;
* track single process memory and cpu usage in a separate histogram window;
* lock/unlock the automatic refresh of the list
* display the processes either in a flat list or in a tree view based on processes ids
and parent ids