JabRef version
JabRef 5.0-dev--snapshot--2018-11-09--master--bab9ae819
Linux 4.14.77-041477-generic amd64
Java 1.8.0_181

• I have tested the latest development version from http://builds.jabref.org/master/ and the problem persists

Steps to reproduce the behavior:
1.Open and entry
2. Choose biblatex source
3.Input Chinese characters
I can't input Chinese characters in biblatex source, but I can do it in other fields and copy Chinese characters from other places to biblatex source.

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