If you use knotty on a terminal with n lines, but the number of tasks displayed by bitbake is some number n+x, where x > 0(I think 0, it may actually be more) then knotty doesn't delete all of the task lines when they are finished. For example try it with gnome-terminal on Fedora-23. Resize the terminal window to be 10 lines. Then change BB_NUMBEr_THREADS to 20 for a fresh build. Run "bitbake core-image-minimal" and make sure that the screen fills up with task output. Then you can feel free to Ctrl-C. Now if you check the terminal scrollback buffer it will have lines for tasks that completed and should have been deleted.
Created attachment 3144 [details] Terminal with 10 lines after build
Created attachment 3145 [details] Terminal with 50 lines after build
This appears to be fixed in 2.2 rc.
Meant to pick fixed, even though not by me.
This still appears to happen with tmux. It may be a tmux problem, but since I don't know for sure, I'll reopen this.
Bulk move from 4.99 or 0.00 to 5.99
This works well for me : ❯ tmux -V tmux 3.2a on ubu-22.04 server.