This is an idea that's been kicking around my brain for many months; A method to quickly place an exact amount of items into a set of inventories.

The execution would be:
Put some amount of an item from your inventory into your cursor, E.g. 20 iron ore.
Then CTRL-Left-Click drag over a set of inventories, E.g. A set of furnaces.
The result being that each inventory would get the exact amount of items that was in your cursor. So the set of furnaces would get 20 iron ore each.

This could also work with CTRL-Right-Click, just that the amount of items that each inventory receives would be half that of the amount in the cursor.

"But what if you have more (or less) items then the amount required to be distributed?"
In the case of more, return any extra items to the players inventory.
In the case of less, I can't find the words to describe it adequacy, so I can only provide this example:
You have 126 iron ore in your inventory, you put 20 iron ore into your cursor. You then CTRL-Left-Click drag over a set of 10 furnaces. There is not enough for all of them to receive 20 ore, so the first 6 furnaces get 20 ore, while the other 4 get none. The 6 excess ore is returned to the players inventory.

This idea would have to be a togglable option within the gui, as you don't/can't always select a full stack of items when grabbing from your inventory.
Perhaps it could be toggled with a keybind for ease of access.

Thank you for considering my idea, and thank you for this amazing mod.