Instead of making the whole PL/SQL Developer open source which, I guess, would ruin your business, would it be possible to make at least all the underlying queries as open source? This way you could focus on developing features in PL/SQL Developer while the community would help you and themselves with all the query-related bugfixing and enhancements. Of course, you guys would remain owners of the queries repository and would be in charge of accepting/rejecting pull requests.
Perhaps even some more enhanced: Making also some other internal string resources open-sourced, for example the bracket-matching regexp's and similar.
Perhaps even some more enhanced: Making also some other internal string resources open-sourced, for example the bracket-matching regexp's and similar.