e Monolith, without error reporting
      //
      // Highlighter needs a port to perform a few different things that can't be done in pure Elm:
      //
      //   1. Detect mouse release outside the highlighter area, to end highlighting
      //   2. Detect touch release outside the highlighter area, to end highlighting
      //   3. Detect long-press to highlight on touch devices when in scroll-friendly mode
      //   4. Handle drag-to-select on touch devices
      //
      app.ports.highlighterInit.sub