Although it might be worth implementing a terminal as an off screen grid of cells, with glyph and colour properties, and then just banging that to the display every so often.
I guess it's the difference between a proper terminal emulator that handles a steam of characters/instructions in real-time, and what I need for the web based dungeon client, which is to translate the IDisplay calls to HTML.
(Yes, I am still thinking about an IDisplay implementation that outputs html)