if an image is drawn from hard disk cache, activity window will completely ignore image size/url on actual page. It will appear as if it does not even exist. This may seem like a minor bug at first. But i have already observed one such website that is exploiting it by means of tricking Safari into loading blocked content. i.e., you blocked banners.site.com in hosts file via 127.0.0.1 then, go to that site. At first the images would be blocked properly. But when you click any links on that site, it would redirect to a different path for the advertisements. Then, it would cache those advertisements. Now when you return to original page the blocked advertisements are now loaded from cache (and hidden from activity window). On Attached file. Download page to disk. open it in webkit. Observe that activity window properly shows the background image. Then click the test page 2 url. You reload a near identical page with same image that loads straight from cache and is totally obstructed from safari's view, activity window does not show any existence of the image.
Created attachment 17599 [details] Test webpage Example Test Page 1
*** This bug has been marked as a duplicate of 11212 ***