Created attachment 782797 [details] Screenshot of the issue in Firefox I've noticed this first for Thunderbird in 898537. It was also mentioned there that this could be a toolkit bug. Than I found out, that Firefox is using also HiDPI images in the system menu (email@example.com, bookmarksToolbar@2x.png...) and this images are also blurry on my Retian MacBook Pro. The PNGs of this icons are totaly fine and sharp. Tested with Firefox 22 and the latest nightly. Interesting to mention is also that the Apple own icon under "Services -> Services Preferences..." is perfectly sharp and not affected.
Created attachment 8457897 [details] [diff] [review] patch The FLAG_SYNC_DECODE change is unrelated but correct and consistent with nsCocoaUtils::CreateNSImageFromImageContainer.
Comment on attachment 8457897 [details] [diff] [review] patch This looks fine to me, and I like the simplification. But frankly my eyes aren't good enough to tell whether or not it works, HiDPI-wise.