WIP Type annotations for tree tabs
Here is some early work on adding type annotations to the functions relating to tree tabs.
working towards: add covering type hints #8073
Looks nice so far, thanks for getting the ball rolling!
Some of your Node[Any] objects should probably be Node[object] instead (i.e. "the content of the node is opaque and we don't access it at all", rather than "any operations are allowed". See Python type hints: Use object instead of Any - Adam Johnson.
Hmm, not sure what's going on. This causes a circular import error, I'm not sure what else to do to resolve the type errors caused by tab_by_idx returning a QWidget. https://github.com/qutebrowser/qutebrowser/pull/8586/commits/5a309efbd4317ca925cfc5ff9bf21f4383e28f9e