Custom pager

[simonlindholm]

Implementing our own less equivalent would make it possible to:

• refresh the display without flicker
• keep scroll position
• capture keystrokes/mouse clicks, so we can add new functionality:
  • highlighting individual registers on click
  • switching between the last K revisions with arrow keys

Would need to support {,page }{up,down}, g, G, q, and probably (annoyingly) search (/, n, N); I don't think the rest of less is useful.