To display complete tasks in Windows version of LeaderTask:
- Press heading of the list of tasks (near heading the black triangle settles down)
- Select the Show Complete Tasks item
The mode of display of all tasks is activated: both active, and complete. At the same time near heading of the list of tasks the square with a tick will be displayed.
To hide complete tasks, do the above described actions once again.
Also you can use a combination of the Ctrl+H hot keys.