What?
Display the stack size of an item somewhere in the UI.Why?
With mods changing stack sizes all over the place, it is hard to remember what setting the stacks filter on a chest will give me until it's actually filled up. Or how many ore I need to fill a train car. Or how many pumpjacks I can carry in my one open inventory slot.Where?
One or more Tooltips would be ideal.How many do I need for X stacks? How close am I to a full stack? How many will I end up with if I limit this chest? Is this a full stack? How many should I request to switch my train from coal to solid fuel? I don't want to fill my train, I just want to send some stone along for the ride... how many can I send? And how many will my drones bring me if I put in a second transport drone?
Mods?
There are plenty which modify the stack sizes: make them more generous, increase certain items, make some smaller.But I did not find any which add the current stack size as a visual element in the game.