Add feature to uncheck all tasks

I am using an Outline page as a checklist what to pack for a trip. The page contains a task list, and for each item that I pack, I check the corresponding task, which gives me an easy overview over what I still need to pack.

When I go on a new trip, I need to uncheck all tasks before starting to pack again. As I have more than 100 items in the task list, it would be great to have a way to uncheck all tasks at once. This could for example be a button in an inline dialog that opens when clicking the “x of y tasks” byline item on top of the page.