I think it would be useful to be able to see potential 'collision zones' on the track by showing the clearance or loading gauge swept out along side the track.
Essentially it would be like showing the track base, but with a user defined distance either side of the track centre line. An application where it would be particularly useful is when setting out passing or run-around loops, and especially with micro layouts and shunting/switching puzzles where the space for track is limited and tolerances on siding length are critical.
The calculations could get very complicated to calculate the actual clearances from overhang and so on, but I think a simple settable distance would be useful.
This is available as the 'Trace' function. On the SHOW tab, tick 'Trace' and set a width.