Since entries of finished downloads are not removed automatically (which I wouldn't like), I think a right-click command "Clear Completed" would be very useful.
What I have in mind is that you could remove either all entries of 100% completed downloads in the 'download queue' tab or all entries of 100% fixed and unrared entries in the PAR2 tab - depending on where you choose to "Clear Completed".
Many thanks again for this great program, which keeps getting even better with every release!