Hold ctrl and rotate the mouse wheel to change zoom. Change tabs. Return on the original tab. The zoom change is lost for me. I bisected this down to the patches for bug 719320.
I can reproduce the problem on Windows7 too. Mozilla/5.0 (Windows NT 6.1; WOW64; rv:17.0) Gecko/17.0 Firefox/17.0 ID:20120814030521
In http://mxr.mozilla.org/mozilla-central/source/browser/base/content/browser-fullZoom.js#89 , It is necessary to adapt preferences name to the latest.
(In reply to Alice0775 White from comment #2) > In > http://mxr.mozilla.org/mozilla-central/source/browser/base/content/browser- > fullZoom.js#89 , > It is necessary to adapt preferences name to the latest. Ah, failed to catch such code by searching "mousewheel.".
Created attachment 652049 [details] [diff] [review] Patch Hmm, this feature doesn't work with SpecialPowers.setFullZoom(). I think that when zoom in or out is performed, Gecko should dispatch a custom event and browser should listen it. But this patch is enough for now.