I am using Sublime Text 3, in this case to edit LaTeX. To further customize the syntax highlighting I would like to define a new scope that simply extends the shipped LaTeX.tmLanguage
(to which I do not have access, not even to read). N.B. I have no interest to write my own tmLanguage-file, not even to download an existing, I just want to extend it, much like overloading a class in Python.
In particular I would like to add meta.footnote.latex
to have a custom syntax highlight for \footnote{...}
(one definition I found in https://github.com/bradrobertson/sublime-packages/blob/master/LaTeX/LaTeX.tmLanguage)