I’d like to be able to double click and select an entire word, even if it includes a ' mark. Such as it's. And be able to use option+shift+arrow (on mac) to select words to the left/right. Currently those stop at the ' character.
Is it possible to modify those boundary characters to determine what constitutes a word?
Only with the wordChars language data, which may not be powerful enough for what you’re trying to do here.
That worked great and is already live in my app tasktxt.com
Is there also a way to remove a wordChar from an existing language?
I am using codemirror/lang-sass and would like to remove the ‘-’ from the wordChars 
No, that’s not possible — at least not without creating your own LRLanguage object for the language.
Makes sense! Thanks!