$ sudo apt-get update
$ sudo apt-get install libmono-system-reactive-window

libmono-system-reactive-window is installed in your system.

Make ensure the libmono-system-reactive-window package were installed using the commands given below,

$ sudo dpkg-query -l | grep libmono-system-reactive-window*

You will get with libmono-system-reactive-window package name, version, architecture and description in a table

libmono-system-reactive-window package basic information: