hello, this is a primarily community-run support forum so it's probably not the right place to request features like this (we cannot implement any features & devs won't read here).

please either use https://input.mozilla.org/feedback for general feedback or if you feel that it's a missing feature in the browser file a bug at bugzilla.mozilla.org.

Hi   !
You've made it clear that you don't want the   'Themes'  add-on;   but maybe you'd consider this one:
https://addons.mozilla.org/en-US/firefox/addon/tab-kit-tab-highlighter/

I appreciate your reply but this add-on is for highlighting active tab. I am needing the entire Firefox Title Bar window to reflect that it is the active Window. Example: I have three Firefox windows up, two on first monitor and third on second. I cannot tell one is the current active window. I think I've got the correct one active I want to type in and one of the other Firefox windows reacts causing problems/errors, I forgot it was, say Firefox Window #2 instead of #1. I guess you get the idea. I am always having to first click in the Firefox window I need to work in to make sure it's active before typing. But thanks again. One note: If I click on something that pops-up a smaller Firefox window, its behavior is correct. It picks up the current setting color from Windows operating system (10) so the small Firefox window's title bar has the active window color.

Couldn't let it go just yet and I'm giving it one more shot:
https://addons.mozilla.org/en-US/firefox/addon/all-tabs-helper/?src=search/

I found a solution that I thought I would post here in case others dislike the Firefox gray title bar. It involves creating a folder in the AppData\Roaming\Mozilla\Firefox\Profiles\{filename}.default area and creating a folder called Chrome and a file inside that folder called userChrome.css. Once I pasted in the code and saved the file and restarted Firefox, when it came up the title bar is now picking reflecting the active Window color I set for Windows 10 window objects. I do not know if there will be fallout due to this but so far so good. If anyone is interested, here is the link: http://www.askvg.com/tip-get-colored-titlebar-back-in-mozilla-firefox-in-windows-10/ It's really too bad Firefox chooses to cover up the default Windows color for the active window to prevent distinguishing that window from all the other (inactive) windows. I would love to know the reason behind this decision and why I had to resort to hunting down, creating and installing code to achieve what should be default behavior.

UPDATE 11/09/16-One drawback I noticed with this approach is the tabs are not easily distinguished, no lines/borders/outline and the color of the tab is the same color as the Windows active window title bar. To improve on this, I used an add-on I've used before but had stopped using. It's called Colorful Tabs and it did the job of changing the color of each tab so they stand out against the background color in the title bar.

Attention philipp and happy112, I did post this question and the solution I came up with in the feedback area using the link philipp provided. thanks and sorry for originally posting here instead of there. i'm new to this whole thing so was not sure where my question should land. Since I was getting suggestions here I wanted to post the solution I came up with in case it helps someone else. Thanks, Hershel

If anyone is interested, here is the link: http://www.askvg.com/tip-get-colored-titlebar-back-in-mozilla-firefox-in-windows-10/ It's really too bad Firefox chooses to cover up the default Windows color for the active window to prevent distinguishing that window from all the other (inactive) windows. I would love to know the reason behind this decision and why I had to resort to hunting down, creating and installing code to achieve what should be default behavior

I think the article you link to gives an explanation for the change. Probably Firefox is not alone in making such a change it looks rather like LibreOffice may have done something similar.