end
      -- If fragment is a filename relative to the current directory, register
      -- a button for clicks on it.
      local filename = rtrim(frag)  -- compute_fragments puts whitespace at the end
      if file_exists(filename) then
        local filename_text = App.newText(love.graphics.getFont(), filename)
        button(State, 'link', {x=x,y=y, w=App.width(filename_text), h=State.line_height, color={1,1,1},
          icon = icon.hyperlink_decoration,
          onpress1 = function()
                       switch_to_file(filename)
                      end,
        })

-- a copy of App.filedropped when given a filename
function switch_to_file(filename)
  -- first make sure to save edits on any existing file
  if Editor_state.next_save then
    save_to_disk(Editor_state)
  end
  -- clear the slate for the new file
--?   print('switching to', filename)
  Editor_state.filename = filename
  load_from_disk(Editor_state)
  Text.redraw_all(Editor_state)
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.cursor1 = {line=1, pos=1}
end

end
function icon.hyperlink_decoration(button_params)
  local x,y = button_params.x, button_params.y
  App.color(Hyperlink_decoration_color)
  love.graphics.line(x,y+Editor_state.line_height, x+button_params.w,y+Editor_state.line_height)

Hyperlink_decoration_color = {r=0.4, g=0.4, b=1}