TL;DR
Dropping (with 'z') items on top of assembling machines and the like should put the item in the output slot.What ?
ctrl-clicking an assembler with an item in your hand tries to put it in the input slots. Dropping with 'z' should put attempt to put items in the output slot.Why ?
I often end up with a small amount of items in my inventory after building a setup, and a reasonable way to reintroduce them to the system would be to drop them in the output slot of the assemblers. This is annoying though, because you have to open up the assembler gui to get there.Ctrl-click is (reasonably) reserved for putting things in the input slots, but this usage of 'z' would fit well with its feel of "get rid of this, please".