The Bug

"Middle Click Dragging" with an item stack in creative mode should duplicate a stack to an inventory slot being click dragged into. However, this only works if and only if the "Pick Block" key bind is set to "Middle Click". If it is set to any other key, say the key "V", neither middle clicking and dragging or pressing "V" and dragging duplicates the stack.

How to reproduce

1. Set the "Pick Block" key bind to something else than middle click, example: the "V" key
2. In creative mode, hold the "V" key with an item stack and click drag into another inventory slot.
3. Hold "Middle Click" and drag into another inventory slot.
4. Hold the "V" key, "Middle Click" and drag into another inventory slot.

Notice that neither of the steps 2-4 produces the expected behavior of duplicating the stack into the slot, whereas only when "Pick Block" is set to "Middle Click" this behavior works as expected.