Display Oracle XMLTYPE in Data Source

I can add a DB Data Source via Oracle JDBC driver and I see tables and data in table editor correctly. Even the CLOB columns are displayed with their content, which can be "Saved as CLOB". But columns with type XMLTYPE are displayed with value e.g. "oracle.sql.OPAQUE@30dac89a" and "Save as CLOB" is not accessible for them. Does any configuration exist, which would display content of this type? It is possible to create a SQL select command, where will be these columns "casted" to CLOB via getClobVal(), but it is not as simple as open data editor on table in Data Sources.

Thanks a lot

Idea 11.1.3, Oracle JDBC ojdbc6-11.2.0.1.0