How can you tell exactly what insecure items are causing a browser to warn about mixed secure and insecure items?

Question

In Firefox, I view my site and get no warnings about insecure mixed content.

Using FireBug, I can see that every request is https.

In Chrome, I

Answer 1

I found that I get the "mixed content"-warning in Chrome even when there is no mixed content, if sometime during the session mixed content was already encountered on the domain.

(Also mentioned here: Why is Chrome reporting a secure / non secure warning when no other browsers aren't?)