Giving a little more input: This must be related to LWJGL. It happened to me that there would be text in the chat box (when I switch tab out & in) which has been previously in memory (by another program) in an unused chunk of the memory (apparently the software did not dereference the string properly). Good news is: By using the command slash (one or multiple times) the bug usually disappears after a short amount of time.
Giving a little more input: This must be related to LWJGL. It happened to me that there would be text in the chat box (when I switch tab out & in) which has been previously in memory (by another program) in an unused chunk of the memory (apparently the software did not dereference the string properly). Good news is: By using the command slash (one or multiple times) the bug usually disappears after a short amount of time.