Select multiple labels
One feature that would make it even better would be to select multiple labels. And even better to choose labels and search using AND or OR and NOT searching (Boolean). I have labels that relate to my family i.e. Me, Son, Daughter, Parents etc. and labels relating to types of accounts, financial, emails etc. It would be good to be able to select two labels for selection e.g.Parents AND email.
Great Idea! I came here to post the same proposal myself and happy to give you my 3 votes.
A worthy example of a user-friendly implementation is the Calibre tag browser: https://manual.calibre-ebook.com/gui.html#tag-browser