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

JabRef 4.4-dev--snapshot--2018-06-15--master--f47b74066
Linux 4.4.0-128-generic amd64
Java 1.8.0_171

Steps to reproduce:

1. Click Alt+4 to open the Web Search panel.
2. Choose e.g. Google Scholar.
3. Try to type something in the white text field just below "Google Scholar" (see screenshot).
   Nothing happens and there is no error displayed.