It is pretty ridiculous in 2019 to be using such a fat and disgusting scrollbar out of the box. I don't know if it's different on other OSes, but on Windows 10 this default scrollbar is ugly and is permanently wasting 17 pixels of screen width alone.

An option should be offered in Firefox (or simply make it the default) to use a more sleek scrollbar, one that is 1-2 pixels thin and is hovering above the page. When the cursor moves near, the scrollbar expands, but still floating with no background under the thumb. This is the most optimal and efficient design available in 2019.

Most people using custom userChrome.js do so for the floating scrollbar, and it just so happens that it broke again in Firefox 69 nightly. Adding this feature built-in would remove the need for annoying and error-prone userChrome.js customization for 99% of users.

I strongly dislike the floating scrollbar. Because the floating scroll bar hides the character of the right end of page.
Any UI should not cover page content!

That's why I suggest that the scrollbar be only a few pixels thin (1-3px max) until the user moves the mouse near/onto it, that way it is barely hiding anything. For me that is a much better compromise than a permanent 17px of dead space. Besides, I don't even remember the last time I had page content reach that far on the right of the screen. In any case, it should be possible to satisfy every needs by providing an option in the browser preferences.

FYI, there is now (well, has been for several months now) a way for users to choose to always show or hide scrollbars in Windows - see: https://blogs.windows.com/windowsexperience/2018/01/24/announcing-windows-10-insider-preview-build-17083-for-pc/ which makes the case for including this in Windows 10 a bit more palatable.

Confirming since it's a valid enhancement request.

(In reply to Nicolas M from comment #0)

Adding this feature built-in would remove the need for annoying and error-prone userChrome.js customization for 99% of users.

Unless I missed something, userChrome.js customization will be removed for 100% of users in Firefox 72, since it can't work without XBL.

AFAICS this is now implemented?

I've set ui.useOverlayScrollbars to 1 a few months ago and been pretty happy.
(Linux)

Yeah, this should work across platforms now:

• On Android, always.
• On macOS by default, depending on your system settings.
• On Linux, using the pref mentioned in comment 9 or after bug 1147847 if it sticks using the checkbox in about:preferences.
• On Windows, using the same pref (though you might want to enable either windows 11 / Linux / Android / macOS scrollbars, if you're not on win11, by using widget.non-native-theme.scrollbar.style).

So yea I'd say this is WFM