Still working on scrolling. Add a clear-scroll (ScrollTop) to make exercising easier.
Removed more dead bits. Correct off-by-one error on triggering scroll-up.
Exit with ^X not ESC and make input mode InputEsc. Progress on scrolling at page bottom.
Ignored pseudo-key 0 (used in startup). Stripped out obsolete content field from SimpleEventHandler.
Revised PutAll by brute force. It now has the correct behaviour but is ugly. Next, time for tests.