Install gkrellm-tz by entering the following commands in the terminal:
sudo apt update sudo apt install gkrellm-tz
Description:
Plugin for gkrellm to show different timezones
This plugin displays the current time in several configurable timezones. It uses the standard names of timezones found under /usr/share/zoneinfo/, e.g. UTC. Timezones can also have descriptive labels which are shown as tooltips. Furthermore it's possible to define a custom time format.
Homepage: http://mamuti.net/gkrellm/gkrellm-tz.en.html
Version: 0.8-1
Section: universe/x11