[mkgmap-dev] Interesting partial success when inter-tile routing

I have managed to route across a tile boundary but the route that was taken was not optimal, it took a much longer route than necessary. Further investigation showed that the "obvious" road to take did not join across the boundary of the tiles but the road that was used must have joined across the boundary. I was routing from west to east and I could route right up to the boundary OK but if I wanted to be on the eastern side of the boundary, the routing was done via other roads and so it reached the destination coming from the east. So, is it just a matter of making the coordinates match better? If so, how do we do that? Rounding? Anyone have any ideas? Cheers, Mark