Start to free some precious keys: alt space

make cua rectangle from prompt. This could free C-RET
for repeat.
This could allow Alt-space to scroll. See.
Alt+Space,Alt+Backspace to scroll.

I think this is the trick. Use the same keys as InfoMode
or other read only stuff. (Alternative would be to set up
the mode for current buffer, but remember we're not modal.)

This means "Repeat" (while currently broken anyway) has to
go to another key, like Control+RET.