The offset added is 82 sprites for monorail and twice that for maglev. This offset corresponds to the number of rail sprites, for each rail type in trg1r.grf.
I was aware this happened with ground sprites, which is reasonable, as in most cases you want a ground sprite to suit the track type. It does not seem so useful that this offset is also added to other station sprites.
One example where I have the problem is the new truck parking tiles. These use TTD's truck sprites. In this case, I can work around the problem by making the tile unavailable for monorail or maglev. Players will have to switch back to normal rail to build truck parking next to their maglev stations.
There are other cases where this workaround is not possible. In the case of some of the animated stations, I would like to use sprites loaded once using Action A and GRM, rather than having to repeat them numerous times for each Action 1 sprite set. I have managed to make this work very successfully except for the problem with the sprite offset.
The only solution I can see in this case, is to use GRM to allocate enough space to have the sprites loaded 3 times, plus the required offsets between them. This works, but it means reserving 192 sprites rather than the 28 sprites that I actually need.
I have searched the NewGRF documentation for help on this, but I don't believe these sprite offsets are even mentioned.
Any suggestions would be welcome.
