while this was obviously a spam-bot answering you, one thing was a viable solution:
create a second interface with a transparent background as big as your game resolution.
show this second interface at the same time you show your inventory. This will block the interaction but you will still be able to trigger the "cursor leaves interface area" action of the inventory.
When closing the inventory, hide the second interface as well.
Make sure the second interface is in the list of interfaces BELOW the inventory.
This list defines the order of the interfaces in the game when they are shown at the same time. When the interface used to block the input is in the list below the inventory, it will be below the inventory in the game, so you can access the inventory.
The forum is a bit deserted by now (bots galore, but not many users). It's much more lively in the Visionaire Discord server. So if you want quicker help and more people answering, consider dropping by there. The link is at the bottom of the page.