I would like to have the opportunity to cluster my active trains in several groups.
eg. I have a lot medusas, some bonus trains from previous era's, a slow carrier train and one poseidon.
When I want to change the timetable of all the medusas it takes a lot of clicking to select them. In this case the 'select-all' possibility in PLUS also select my unwanted slow trains.
The idea is I'm able to select a previous selected group of trains and then can change the timetable of only those trains with one click.
Now I can order my medusas in a group and let them travel around on my network to drive competitions and join the slower trains in a group leaving them on the old scedule.