Whenever a player opens any inventory, a packet is sent. This is very useful to use on the server, as you can do things like change which items show up. Every time they close their inventory, a different packet is sent. This is very good to know, as things like anti-cheats can prevent you from moving while you are in an inventory. This system works well, except for one situation: opening your own player inventory.

This would be very useful for the server to know, as anti-cheats could very easily track when you have any inventory open. It would also allow sending things like chest-guis right when you open your player inventory, which would allow for some interesting mechanics. For example, you could double the size of your own inventory, by always showing a single chest whenever you open your inventory. You could also disable your inventory, by immediately closing it whenever it is opened. This would allow you to not get distracted by looking through your inventory when you are in the middle of something like a mini game.

I think adding this one packet could help servers be a lot smarter and more versatile, and would allow for a lot more customization that is currently not possible.

Also note that there is already a close inventory packet sent whenever you close your own inventory. This packet always sends the window id 0, so sending that same window id in an open window packet would make the most sense.

I am not sure if this applies to the newest snapshot, and I couldn't find any preexisting reports of this bug. All of the research/testing I have done has been against java edition. I have no idea what this is like for bedrock edition.