As a long term user and thanks for Notepad++ I’ve used it for SQL, C++, Java and more.
I’d really love a Dart (Flutter) PlugIn or Langage for syntax. Any ideas? Is there one? Is there a place to add it to a wish list for Notepad++
Such syntax highlighting is done by the Scintilla component of Notepad++. Scintilla is a separate project controlled by different developers. That component would have to support it first, then Notepad++ could put the hooks in to access it.
That said, I didn’t research whether or not Scintilla already supports the language you’re asking for.
Idea 1: Make a UDL (User Defined Language) – which is relatively simple, especially if you follow the links in the UDL dialog/panel to https://ivan-radic.github.io/udl-documentation/ , which describes each filed in the UDL definition in detail.
Idea 2: Since you apparently know C++, you could also write a lexer plugin if you cannot find one elsewhere.