I know this topic is outdated already but I was wondering recently how people fill the furnace SO fast as they do that I thought something like the automated fill-in might have been implemented. That`s why I looked it up. (How do they do that THIS fast?)
Is there some command to make a makro for?
idk something like

/target furnace
/put iron ingot, furnace

something similar to that attack makro

/target next alive
/attack bloody

Isn't that worth a thought?

Another idea would be to implement a standart.comination of keys for inserting a single object into the container that is open atm.
Like Shift + left click gives you a single object of a stack but it does not place it in the container open at that moment. And yes, it would be a great improvement.
(at least as great as a "make an npc-sell become undone"-button, haha - i sold my things so often accidentially )



---> edit: I just found out that i dont have to actually click into the correct container slot. an item dragged with shift+LMB combination placed on top of a full slot in the furnace will find its way to a free slot by itself. so... no need to "improve" that any more.. sry for the inconvenience caused haha ... so THATS how people fill the furnace so fast