Install ibus-libthai by entering the following commands in the terminal:
sudo apt update sudo apt install ibus-libthai
Description:
Thai input method engine for IBus based on LibThai
ibus-libthai is a Thai IBus input method engine based on LibThai library. . It supports Ketmanee, TIS-820.2538 and Pattachote keyboard layouts, and can check and correct input sequences with three levels of strictness.
Homepage: https://linux.thai.net/projects/libthai
Version: 0.1.4-4
Section: universe/utils