A simple stopwatch plugin for Xfce panel.
Add xfce4-stopwatch-plugin to the panel. Press the “play/pause” button to start and stop. Right click on the plugin and select “Reset” to reset it.
There are no ways to configure the plugin at this time.
The start time and state will be saved when your panel quits and restored next time it's running. This means it will continue even if you power off and power on your computer.