[MCM-861] Inventory desyncs with client causing commands to fail when trading.

Partner Rank:

Partner Team Reporting:

Jigarbov Productions Inc.

Verification builds and Platforms:

1.13.31
1.14.0.3 Minecraft - Publish_3240615 Win10

Summary:

Clearing items when trading with villagers causes inventory desyncs and problems

Impact:

Infinity Plumber uses this mechanic to unlock items. It is part of the realms + opening set of maps and will cause issues with players who use this map. It also exists in many other maps on the store as there are items we want to give players that simply don't work in villager trade tables.

Repro Steps:

Open the repro world (attached).
Get some items from the command block buttons
Trade with the villager, make sure to use the window next to the trade button.

Observed Results:

When using the window next to the trade window, to "click" it into your inventory, some weird stuff starts happening. Items will appear in your mouse spot that you didn't click, it will take some of your items and those items will return when you leave/return to the game. The clear wont work on items in your inventory (because they're really ghost items that aren't there.)

Expected Results:

Regardless of the way you trade with a villager, the items should appear in your inventory or mouse spot.

Screenshots/Videos attached:

video: V1 Villagers: https://youtu.be/eZf9mUBhHls

video: V2 Villagers: https://youtu.be/GWdNYbP7oF4

world attached

Regression Builds:

Wasn't able to repro in 1.12.1.1

Notes:

It seems that holding shift when trading in that window works fine, same with trade button, seems to be only when clicking on that item window to have it in your "mouse" slot Happens with both V1 and V2 villagers.