I think that perhaps the troubles which can be encountered are due to dual definitions in old and new editor.
I don't think so since both editors are using the same mimeTypes.rdf and the same RDF format. I'm convinced that the trouble is caused by wrong file type definitions made with the old editor. There a several possibilities to make something wrong and then your settings simply do not take effect.
I think that the new editor is nice, but is lacking the feature of adding types. For example, application/pdf, when added in old editor, allows to open with the default program, what K-Meleon always do without a manually created type, but if you don't use the old editor, you have always the choice question (download or open).
Yes, that's right. The question is whether this file type addition is so important that we have to include the old editor by default.
Facing JamesD's comment - you can assume him to be a more experienced user - I see the situation something like this:
- 95% of the users don't know what a MIME type is, never used a MIME type editor and wouldn't miss a MIME type editor if there were none.
- <5% do care about MIME type settings, but frequently fail to succeed with the old editor and frequently complain that "it doesn't work".
- The rest knows how to use the old editor or succeeded due to good luck. application/pdf is a good example because you can't make much wrong with this type. (*)
I guess that more than 95% would be satisfied with the new editor. The others could install the old editor as an optional package. Thanks to your Extension Setup that could be done with a few mouse clicks.
(*) Am I right that you are not using the Adobe Reader? Since, when you have installed the Adobe Reader, the Adobe Reader plugin is handling application/pdf files by default. The application/pdf type can then be configured in the new editor.