Add window outside click handle

[Spliterash]

There is currently no way to catch when the player has clicked outside the window. I want to fix it

Im not test this, because i dont know how to compile this project (where i should get org.spigotmc:minecraft-server:csrg:maps-spigot-members, and it have another groupid in maven and packages, rly idk how)

[NichtStudioCode]

I've implemented this properly in 13bef06660b4542845a26b13acc97c650c8ddfb7