If you highlight part of your reply text and click the quote icon like the old days, it quotes your ENTIRE new post, not just the highlighted text. So I guess for practical purposes, the quote button is broken.
If I manually enter the quote /quote tags it works as expected.
Just tried it again. This is the result. Note the highlighted text is still highlighed after clicking the quote button. That highlighted text is all I expected to be in the quote, but it quoted my entire post.