Compared to the siede-bar, I find the Repl bottom-bar much better to work with. But when the output section overflows, contrary to the side-bar mode, I cannot scroll down in the bottom-bar to get the results. (tested in Chrome, Firefox, Safari).
Maybe a "Clear" button, clearing both the edit and output sections, could resolve this?
(aside: just a gimmick, but an outstanding one, is Repl on mobile. But I cannot do Ctrl+Enter on my mobile. An "Execute" button would be cool.)