the GUI editor should be able to use custom parsers
According to MoinMoinBugs/GUIEditorCorruptingNonWikiPages, the GUI editor just doesn't work with plugin parsers, and the fix is apparently going to be to not allow the GUI editor to be used with plugin parsers.
However, it would be pretty easy to make the GUI editor work with most plugin parsers, if plugin authors were willing to do a little more work.
I've already tried a few lines of changes to have the GUI editor page use the configured parser instead of always grabbing the moin wiki parser, which seems to work quite well in terms of gettting non-moin markup displayed correctly in the GUI editor. The other half is making the process of converting the GUI editor's HTML back into markup also plug-able. I suggest offering the option for parser authors to implement the HTML -> markup conversion. Moin can then decide the offer the GUI option based on whether the current parser implements the HTML -> markup conversion.
- This sounds pretty much like somebody has not looked at the code which actually does the conversion for the wiki markup. It is a lot of code and not written in a trivial style. We could think about making it modular, though.
We will try to make quite some mimetype dependant stuff more regular and OO in moin 2.0+. We maybe don't do the stuff you mentioned first, as there is no html -> rest converter anyway, but it might be just done while generalizing the whole stuff.