Steps to reproduce:
1. Place any right-clickable block or item into any slot of the hotbar
2. Go to the Survival Inventory tab
3. Drop the item (Either by dragging it or pressing Q)
4. Exit the inventory
5. Right click on the ground with the same slot the block/item was, you should see that the item is still saved in that slot.
Code analysis by @unknown in this comment.
Linked issues
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The following is based on a decompiled version of Minecraft 1.10 using MCP 9.30.
Server-side it looks like the intended behaviour is that the item count is not reduced (net.minecraft.network.NetHandlerPlayServer.processCreativeInventoryAction(CPacketCreativeInventoryAction)
, slotId = -1), however the client reduces the count (net.minecraft.client.gui.inventory.GuiContainerCreative.handleMouseClick(Slot, int, int, ClickType)
).
Relates to MC-2912