I think this is a regression from the swipe animations, but not sure what the right component for it is. STR: 1. Close one of your tabs. 2. Open a link from another app (such as Thunderbird) Sometimes when Firefox gains focus after step 2, a new tab is opened, showing the contents of the previously closed tab for a few seconds while the real page is loading, and once the page is rendered the previous content disappears. This seems to be timing dependent, as it doesn't happen for all closed tabs, but it happens for all websites regardless.

This sounds pretty bad. Unfortunately, I've been unable to reproduce this. I've closed one tab, multiple tabs, tabs with lots of content and some with barely any. Still, the new tab is always blank when I open a link from another app. Is there something about your setup that could make the difference (add-ons)? If you can reliably reproduce, is there a regression range? Thanks!

I can't reproduce this reliably, unfortunately but I see this all the time in my daily browser usage, mostly with Bugzilla links that I open from Thunderbird. I will attach my about:support which shows the list of my enabled add-ons among others.

Alright I finally realized how to reproduce this. 1. Click on a link in an external app. 2. As soon as Firefox window receives focus, start a horizontal swipe. 3. The swipe animation is rendered until the first frame of the new content is painted. If you swipe a very small amount, this will give the impression of the old content being rendered. And I do that unintentionally all the time (see bug 939250.)

Huh, weird. Thanks, Ehsan! I can repro this now. It doesn't seem to matter what was displayed in the tab that got closed. I can repro even without closing tabs as long as at least one snapshot was taken (i.e. the browser history has a length of at least 2).

(In reply to comment #5) > Huh, weird. Thanks, Ehsan! I can repro this now. It doesn't seem to matter what > was displayed in the tab that got closed. I can repro even without closing tabs > as long as at least one snapshot was taken (i.e. the browser history has a > length of at least 2). Yes that is what I'm seeing as well. Sorry for the false alarm about the contents of the closed tab, I was not entirely sure what the thing that I'm seeing is!

The code in question here has been removed in bug 860493.