Finished the Fetch Tile routine today, after banging my head on the desk repeatedly (in actual fact, it was just a process of working on each part of the routine in turn). Now the editor can intelligently display the cursor over the correct tile and adjust the scroll register so that the relevant tile is always in view.
Finished up by tweaking my menu code so that the keyboard shortcuts are justified properly (they used to be right-justified, now they're tabbed, for anyone remotely interested!).
