uhhh this looks like the bg tabs are for some reason not fully opaque. This messes up the text because of subpixel anti aliasing onto a non-opaque bg. Pretty sure your screenshots show you're using a custom theme. Which one is it? This is likely another place we need to force the theme-provided color to opaque.

Yeah, that's definitely the result of rendering text onto a transparent background.  As Evan notes, this is presumably due to a custom there -- let us know which one you're using.

I am using 'Space Lagoon' theme: 
https://chrome.google.com/webstore/detail/space-lagoon/balmhbonohcljflhinodkindpfmcdlie


PS: Took me a while to find out which theme I am currently using. This post was useful: https://productforums.google.com/d/msg/chrome/QwiuHnwOk1U/Kl4Ko2mVAJMJ

thanks. I don't see this on Linux 51 or 53 so it's likely cros-specific (would be worth checking win and Mac).

Peter if you can't repro on win feel free to re-assign to me.

Indeed; I'm also not seeing the issue on Linux. I looked up the theme ID on my Linux box since it's a bit easier.

Doesn't reproduce on my Win 10 Dev build.  But does reproduce on my Chromebook that's on M53.  So it looks like this is an unfixed, CrOS-specific bug.

I don't know what would be CrOS-specific about this.  I'll try to debug a little locally on Windows to see where the tab color is being forced to opaque.

Retargeting CCs at more appropriate people.

Part of the issue is that the theme provides a custom IDR_THEME_FRAME, but it's not used on my Windows 10 machine because ShouldWindowContentsBeTransparent() is true -- in other words, the theme isn't forcing us onto the old opaque frame.  So the background tabs are drawn as tinted versions of the (opaque) toolbar color.

I suspect this may reproduce on Win 7 in classic mode, and if so, it would suggest that it's because both that and CrOS treat the window contents as "not transparent", so we'd use the custom frame image, so the background tabs would become copies of that background image tinted with TINT_BACKGROUND_TAB.  I bet the background image has a non-opaque alpha channel in it and that's the issue?  Not really sure.

Do we have a tool to unpack theme .pak files and play around with their contents?  It's really annoying to be trying to figure all this out inside a debugger.

Hmm.  I can't repro if I hack the code locally to force the opaque frame on.  So I guess I don't know why this is occurring.

I think someone is going to have to debug on CrOS and figure out what's up.  I elect Terry.

Hi!

I'm also having this issue with with the last version of Chrome OS (stable channel), using a theme I have developed. If you need any help to find out what's causing this, I can send you the theme's manifest.

BTW, before this happened to me only when I did not have the Chrome window maximized, but since Chrome 53 (I don't remember which version, but more or less) it happens in all windows.

I can't reproduce this problem in MacOS/OS X.

Hi again!

This issue hasn't been solved yet. Is there any update on it? Also, is there any way I can help get this problem solved?

Thanks ;)

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Tom/Omri, can you please help to triage this issue?

Stéphane, it seems we have a problem with anti alising text on semi-transparent backgrounds, I've also seen this recently on the Launcher.
Is there anything we can do here?

This is probably more appropriate for Vlad's team

Chatted with marcheu@ offline, it looks like this could be from anywhere in the stack which could be any of many different teams :-/
If this only happens on ChromeOS, it's likely in Aura.

the issue with blurry subpixel text rendering onto non-opaque backgrounds is long standing and had long been understood to be unfixable. The way we would fix it in this case is either to force bg tabs to be opaque (ignore the alpha channel that the theme provides) or to disable subpixel AA on tab text when we detect that this will be a problem.

Omri, I need you help figuring out how to approach this.