gtk3-im-libthai software package provides GTK+ 3 Input Method Module using LibThai, 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 gtk3-im-libthai
gtk3-im-libthai is installed in your system.
Make ensure the gtk3-im-libthai package were installed using the commands given below,
$ sudo dpkg-query -l | grep gtk3-im-libthai *
You will get with gtk3-im-libthai package name, version, architecture and description in a table
| Distro | Ubuntu 16 04 lts xenial xerus |
| Section | Libraries |
| Package | gtk3-im-libthai |
| Version | 0.2.1-5ubuntu1 |
| Description | GTK+ 3 Input Method Module using LibThai |
| Sub Section | Libs |