Some popular content-blocking addons are failing to work with background thumbnails. AdBlockPlus is known to not work, and there is suspicion that other popular ones, like NoScript, Ghostery and Request Policy may fail for similar reasons. We should look into why they fail and see if there is anything we can do to fix them. More context at https://groups.google.com/forum/#!topic/mozilla.dev.platform/2WHROKmyQso and https://groups.google.com/d/msg/mozilla.dev.platform/2WHROKmyQso/_bOhXmf-gQIJ

Does this also affect the Firefox built-in tracking protection?

(In reply to Johannes Pfrang [:johnp] from comment #1) > Does this also affect the Firefox built-in tracking protection? Apparently, since I have visited sites where the tracking protection kicks in, but when they show up in the "New Tab" page, no sign that tracking protection does its job.

I'm confused by this bug report and haven't been able to get a good grasp of the issue by reading the linked threads. Could someone please provide steps to reproduce and explicitly state the expected and actual result?

I don't have specific STRs but I know what the problem was/is (I don't know if still happens): the tile created to show up on about:newtab is created without the effects of ABP, so the thumbnail is full of ads, that when you visit the page with ABP enabled you don't see.