Though JChemPaint is already very useful, it is not without errors. The development team is too small to make the source code 100% bug-free. So, at some stage you will find bugs (apologies for that in advance). However, the open source community is known for its quick response to both acknowledging, and fixing bugs. The JChemPaint team aims to uphold the same standard - which is sometimes a bit difficult as there is so much to do. Nevertheless, we appreciate it very much if bugs got reported; the JChemPaint team does solve many bugs in each release. Bug reports can be filed at http://sourceforge.net/apps/trac/jchempaint/ ("New Ticket", type should be defect).
We are always happy to hear about people's ideas. You can use the bug tracker at http://sourceforge.net/apps/trac/jchempaint/ ("New Ticket", type should be enhancement) to request features. You can also start a discussion on the mailing list at http://lists.sourceforge.net/lists/listinfo/cdk-jchempaint or mail developers listed at http://sourceforge.net/projects/jchempaint/.
Debugging is a lot easier when debug information is supplied along with the bug report. JChemPaint can be started to get debug information like this:
java -Dcdk.debugging=true -jar jchempaint.jar
This will create a cdk.log file which can be attached to the bug.