Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.cursor1 = {line=1, pos=1}
  -- keep a few blank lines around: https://merveilles.town/@akkartik/110084833821965708

  elseif Current_app == 'source' then
    if run.mouse_wheel_move then run.mouse_wheel_move(dx,dy) end
  if Current_app == 'run' then

  if Current_app == 'run' then
    if run.mouse_wheel_move then run.mouse_wheel_move(dx,dy) end
  elseif Current_app == 'source' then