$ sudo apt-get update
$ sudo apt-get install libgtkhtml-editor0 

libgtkhtml-editor0 is installed in your system.

Make ensure the libgtkhtml-editor0 package were installed using the commands given below,

$ sudo dpkg-query -l | grep libgtkhtml-editor0 *

You will get with libgtkhtml-editor0 package name, version, architecture and description in a table

libgtkhtml-editor0 package basic information: