In 4.0.10, when adding Foreign key reference, only keys from the current database are shown. Option is missing to refer to keys from other databases.
This feature was implemented in version 4.1.0 and is available in version after that. See https://github.com/phpmyadmin/history/blob/master/ChangeLogs/ChangeLog-2013 Latest stable version is 4.2.2.
This feature was implemented in version 4.1.0 and is available in version after that. See https://github.com/phpmyadmin/history/blob/master/ChangeLogs/ChangeLog-2013
Latest stable version is 4.2.2.