Currently, the only way option we have is "Enable spellcheck for New Documents". I use this app to take notes in my college courses. I am constantly switching between writing calculus equations and annotating computer science lecture pdfs. The app currently always tries to spellcheck my equations and thinks that they are words. I want to be able to enable spell check for a specific document, or even toggle it for a certain folder (Off for Calculus, on for others).