Hey Eric,
I have added my first real code for submission to LO :-) It's in gerrit: https://gerrit.libreoffice.org/2476.I'm going to review it in the next days.
so here is the inital review for your change. Your patch looks already quite good but there are some small changes necessary before we can merge it. First we need to move the new values in CurveStyle.idl to the end and remove all the GNM_* values. Moving the values to the end ensures that the old values stay unchanged which causes as little trouble for extension developers using the API as possible. The import for files written by gnumeric should map the values to the corresponding ODF values and during export we only want to export them as ODF and never into the gnumeric namespace. This also means to remove all the references to the GNM_* values in the other source files. For that to correctly work we need to register the gnumeric namespace and map the elements in the chart namespace and the elements in the gnumeric namesapce to the same UNO attributes. Your current export code is producing invalid xml files because you were exporting the gnumeric values without registering the namespace. However this problem should be gone once we no longer export elements into the gnumeric namespace. Additionally we need to take care of the ODF version during export and make sure we only export it into ODF1.2 extended. I think Thorsten was fine with exporting the elements into the chart namespace but only for ODF 1.2 extended. The code in AreaChart.cxx looks mostly good and I will have a final look at it when all the other problems are fixed. Additionally it would be nice if you would provide at least one of your test documents from gnumeric and one of your test documents for normal ODF as MPL/LGPL licensed test documents that we can add to our test file repository. If you are interested it would also be nice if you could add a test case for it to our new chart2 import test at chart2/qa/extras/chart2import.cxx. Please let me know if I should help you with any of the above tasks. I can take care of them if neccesary. Thanks a lot for your great work. It is highly appreciated and feel free to ask for any help you need. For the UI part of the task it might make sense to first convert the relevant dialog to the new UI format and then add the new elements into it. Regards, Markus