The bug
The trading window remains open when a villager moves outside of the interaction range.
How to reproduce
Spawn a villager and a zombie
Start trading with the villager
→ ❌ The window stays open even after the villager left the interaction range
The trading window in the screenshot belongs to the villager in the right corner.
Is this still a concern in the current Minecraft version 14w18b / Launcher version 1.3.11 or later? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases.