User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:64.0) Gecko/20100101 Firefox/64.0

Steps to reproduce:

I tried to enabled the Dark theme to make Firefox behave like a dark/night themed app, as is growing in popularity. I already enabled Dark theme in Windows 10, and now I also enabled the dark theme from within Firefox

Actual results:

Not much. The customize screen become dark themed, and that's about it. Since the title bar and tabs already were dark themed by the Windows dark theme setting, Firefox sort of stopped there and doesn't dark theme anything else.

Expected results:

The Options and Addons tabs should also be dark themed.
The scrollbar should be dark.
addons.mozilla.org should respond to dark theme.
The right-click context menu should be dark.
Reading Mode should be dark.
The Page Info window should be dark.
The Library window should be dark.

And much more I'm sure.

Also please refrain from marking this bug as duplicate of another one which describes much fewer UI elements to be themed. The guys over at Thunderbird managed to do this, and I hope Firefox devs are not like that.

Dude, really? You have to be that way?

What wrong with bug 1519547?

Look at the list I gave in my first comment. Bug 1519547 only describes in-content pages, which isn't the same. There's overlap, but it's not a duplicate.

Let's add another one:

bugzilla.mozilla.org should respond to dark theme :)

Tim's bug is a meta bug (which has been reported before yours), meaning that it will incorporate the same feature you are talking about. On top of that, we prefer to create a bug per change in general.

About bugzilla.mozilla.org, this should be a separate bug.

(In reply to Martijn from comment #0)

The Options and Addons tabs should also be dark themed.

Bug 1519547

The scrollbar should be dark.

No bug filed for this yet, but bug 1544025 might cover it.

addons.mozilla.org should respond to dark theme.

https://github.com/mozilla/addons-frontend/issues/7907

The right-click context menu should be dark.

Bug 1450046

Reading Mode should be dark.

Bug 1187696

The Page Info window should be dark.
The Library window should be dark.

I don't think we'll be investing effort into these two dialogs. This might be implemented natively on MacOS though, using the MacOS 10.14 SDK.