I wrote a very basic WML syntax highlighter for Vim: forum post (including syntax file).
What is needed now:
- More error detection.
- Better support of Formula.
- Matching of tags to support folding.
- Merging with the current Lua 5.2 syntax.
- Documentation, Vimball.
It would be great to convert/use a WML schema file in a plugin to detect standard keys in a tag. However the schema project need some more work first.
If you have any remark, you can drop me a line on the forum or on the talk page.