blackbox software package provides Window manager for X, you can install in your Ubuntu 16.04 LTS (Xenial Xerus) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install blackbox
blackbox is installed in your system.
Make ensure the blackbox package were installed using the commands given below,
$ sudo dpkg-query -l | grep blackbox *
You will get with blackbox package name, version, architecture and description in a table
| Distro | Ubuntu 16 04 lts xenial xerus |
| Section | X Window System software |
| Package | blackbox |
| Version | 0.70.1-30 |
| Description | Window manager for X |
| Sub Section | X62 |