There's a good chance that one of the few modes in Classic Theme Restorer can alleviate this problem.
Matter of POVs. Imo you missed the lack of transparency on w10. Aero glass works, sure. But it's an hack used likely by the 0.01% of the W8 or W10 users.
If that's the case, then why does transparency work fine in windows 7 with firefox 40? They're obviously doing a check: If OS version < 10 enable transparency, else turn it off. So I need to trick firefox 40 on windows 10 to think it's running on windows 7.
I'm willing to live with it for a little while at least, mainly because in the past few hours performance has been great, runs a lot faster (and it wasn't slow to begin with).
Not a surprise, it only makes sense since the build-in Aero style/theming is broken in Windows 10, and the gray looks better than the forced white title bars. Of course it's ignoring the window color and Aero glass since it's using custom rendering.
Of all the programs I have installed, firefox 40 is the only program that ignores the window color, with no obvious option to disable the "custom window rendering." There is no excuse for that.
Visual Studio ignores it. Office ignores it. Photoshop ignores it. There's a whole bunch of programs all using their custom window rendering that cannot be disabled. I know, it's not good practice from a UX guideline perspective, but that's just the way it is, even before Windows 10.
went to the thread list. saw exclamation icon and thread title: "firefox 40 ignores --- " (my eyes read this at first glance), enter thread... and see it's no big problem and i continue installing it instead of chrome.
programmer releases new version of application that finally matches ui with the actual os, even keeps the classic respective ui in other os's. someone's using not officially suported and forced transparency looks (or some dART theme) on os's windows. sees the new application version not supporting that. creates thread: -insert app name- -insert recent version- not supporting my theme. and extends it to: what are they smoking? developer's fault. totally. mozilla should apologize. oh. wait. no.
An option in about:config to override the default and instead use system colors wouldn't be imposing on anyone especially since it gives you a warning when you open it. For a moment, let's forget aero glass. Should I not be allowed to use my almost black system window colors if I want to? Should I just shut up and like what the designers make? I mean, I can use Pale Moon, Chrome, or lots of other browsers but my favorite is firefox. So I fixed the problem by using FF 38 ESR which has all current security updates. I'm sure within a month or so I'll figure this problem out or someone else will. I just think it's stupid to not allow system colors. And that, man, is like, my opinion.
What's the deal? Since FF35 (?) they completely ignore the scheme and give instead a smoke gray color for aero in Windows 7... I dont see a problem, Photoshop does this in a more "intrusive way", and honestly, the dark theme aleviates my poor eyes... That gray title bar is better than the default crappy look of Windows 10... The only problem this has is that, if you choose a non-aero theme with FF open, and you go back to Aero, the titlebar buttons become unresponsive... weird stuff huh?