The reason they ARE stacked differently is because charcoal burns slightly longer than coal.
Nope, considering I just spent an hour fiddling with the coal class so I would know. The only difference is the damage- the furnace gives charcoal the coal id but 1 damage when it creates it. It uses that to differentiate the tooltips. That's the only difference. Same class and same burn time.
Thanks for this. I too am one of those people that dislikes double stacks of basically the same items, like coal and charcoal in my inventory.
Maybe you can tackle wood next and make it so that all 3 types of logs can be stacked in one stack. I figure until Notch does something that makes the different trees have a meaning in the game they should really have just been a graphical enhancement instead of making them stack in different stacks.
Hey, I hope nobody minds but I decided to update this mod for 1.4_01.... I had encountered the same problem that I don't know how to edit the characoal to just be coal so if you burn wood it will simply turn into coal now, if I can I will try to make it so that you can just put characoal in the crafting table/inventory and make it into normal coal...
For now this is the mod however: http://www.mediafire.com/?tnx26irj0z17nda