Hi,

is it possible to implement a function that after specified torrents are completed, the computer stop the program and shutdown entirely?

Torrents thrive from 100% peers giving back to the community.

You have two ways: easy and not specific (scheduler) and harder manual but most specific (shell completion commands)

1) scheduler: go to the scheduler tab (clock) and Add a new schedule.
1.1) Select cycle (when to execute): Once or daily and set a time when you think a transfer will complete.
1.2) Add: Shutdown > Shut down system when all downloads complete
Repeat the same but set the scheduled time 1hr later and simply instruct to shut down the system (unconditionally, in case the transfer does not complete in time and you dont want your PC to run over night)

Drawbacks: you can't select a specific torrent

Method 2: the manual one
Go to Options > Transfers > Files > File completion shell commands. the xfer: parameter only runs when a transfer has completed.
Then write a script that will shutdown when it sees 'transfer name == saved name' it will shutdown the computer. I recommend to use the actuall shell (Bash) for this instead of cmd.exe if you are on Windows. There're many tutorials and all you need to do in the simple case of 1 transfer > shutdown is to compare a text string with the one you previously saved.

Overall I agree Tixati could have torrent completion events in its scheduler but I think youd be faster on your own.