GSD 5 completed action/project

[Wurste Bear]

Hi, as a relative newbie, I would like to know which shadow tiddler(s) and where I need to adjust in order to achieve a strike through of titles, once an action/project is completed. I like the design of the task management example, where completed tasks are shown as 'strikesthroughs'. Thanks for this magnificent little piece of software; it really outshines other software with the inherent huge flexibility.