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Hello Gary, can you see if this is fixed/better in today's nightly (out in a few hours) now that bug 908796 was backed out to fix bug 910983 (I think this is a dupe of it).

The back out did not fix the tabs. It appears that the anti-aliasing at the areas that I indicated on my screenshot need some fixing. There are too many dark colored pixels on the tab that drop below the nav bar border.

This problem might be another case of HiDPI. If I set layout.css.devPixelsPerPx = 1.0, which I assume is 96 dpi, the tab curves look better. Either way the tab borders are different then the Navigation bar border. The Nav border seems to be darker. I need a dpi of 120 in order to read comfortably so 96 dpi is not an option for me.

To really see what the problem is look at a screen that is inactive. The flow from the tabs to the nav bar on both sides really 'pop' out. You might need to use a HiDPI like 120 to see the problem.

Do you still reproduce this in the latest nightly ?

Yes I can. You can really see the problem if you apply this Persona: https://addons.mozilla.org/en-US/firefox/addon/brushed-metal-xp/

(In reply to Gary [:streetwolf] from comment #4) > To really see what the problem is look at a screen that is inactive. The > flow from the tabs to the nav bar on both sides really 'pop' out. I see the problem only above of the curve, but not below like in your screenshots. But I use 2 normal 22'' displays, not HiDPI ones. 29.0a1 (2014-01-31), win 7 x64

I used the pref 'layout.css.devPixelsPerPx' = 1 to essentially set the dpi to 96 which is not HiDPI. Everything displays fine this way. So this particular problem is another case of a high DPI causing visual problems. I see lots of this sort of thing since Fx started using the OS DPI in Fx way back when.

btw... you might be able to run Fx in HiDPI mode by setting the pref above to any value above 1.0. 1.2 might do it.