I am seeing this same in 1.9.2 - Fedora 23 linux
[rhudson@tiros ~]$ java -version
openjdk version "1.8.0_91"
OpenJDK Runtime Environment (build 1.8.0_91-b14)
OpenJDK 64-Bit Server VM (build 25.91-b14, mixed mode)
I can't paste into the seed field or the world name field (I generate names and usually use the same for the initial seed)
I can paste the info into gedit. but ctrl-v and shift-ctrl-v do not paste into Minecraft.
I like playing with the "spawn-monsters=false" in my server.properties.
When lighting strikes mounted skeletons are generated. I consider this a bug since spawn-monsters is false. I don't mind finding monsters near dungeons when I go looking for them, but this is not right. I end up going into creative mode to kill the skeleton/horses.
Please do not spawn any monsters on the surface while spawn-monsters=false.
Server and client = 1.9.2.
This is not so bad for using a generated name (easily typeable), a little harder for a seed which is a string of numbers, but down right difficult if you want to paste a custom world string.