I'll see if I can verify and fix this. Thanks!
I've considered this, and I'll try to implement it soon; there are just some issues I need to work out first (e.g. what if multiple routes are loaded? what if the route file is gone? etc.)
This would be difficult given the current implementation, plus it's hard to do while driving, plus it gets in the way of the context-sensitive "click-and-hold" menu, plus it's strenuous on the screen (can create scratches, especially if done while driving). I've been meaning to investigate this, but there are more pressing things (like bugs) that I need to work out...
It is not (yet) open source, but the functionality it performs may soon be moved to Maemo Mapper itself (if I can work out the string parsing issues efficiently enough).