I don't really know if this is already (or even) possible. But i like to use single key shortcuts like "S" for scrolling down in firefox. There i use vimmy for that. But of course i need the S key for typing, and vimmy can differentiate if focus is on a text field or not. It would be awesome if BTT could recognize text fields also so single key shortcuts would only work when i don't need to type something.
Thanks and have a nice day.