How to change scrollbar thickness in FF Quantum?[Linux]

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Post Posted August 30th, 2018, 6:46 am

It is 2018 and Firefox Quantum's thin scrollbars are driving me nuts (on Linux). Is it something that can be changed in Firefox itself like in this outdated link (links back to mozillazine), or at the level of the OS itself, ie KDE 5 in this case?
Last edited by LIMPET235 on August 30th, 2018, 6:55 am, edited 1 time in total.
Reason: Added [Linux] to the title.


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Post Posted August 30th, 2018, 11:23 am

In some Linux OSs the Appearance (themes,fonts, etc) are usually picked up by Firefox.
You might start there and experiment a little and see what agrees with Firefox.
You can also alter the theme used in Firefox or possibly try others.


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Post Posted August 30th, 2018, 4:20 pm

Does Firefox look unthemed and missing scrollbar arrows?

Firefox since 46.0 and later has required GTK 3.4 (three.four) at minimum to run though most people probably have GTK 3.12 or later by now.

Due to the GTK3 requirement Firefox needs a GTK3 theme to theme it as GTK2 themes will not work. Yes I know you said KDE however Firefox is more of a Gnome app.


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Post Posted August 31st, 2018, 6:37 am

@James - doesn't it depend on the modifications by the OS's version of Firefox?
This system theme is still picked up by Firefox in this earlier version of Liinux Mint 17.x, though still narrow (about half normal width) with arrows which appear and disappear with the mouse over. There's no GTK3 on this system and GTK2 is apparent under /usr/lib/firefox, changes to system theme affects Firefox display.
On other later systems it appears the same or is invisible until you place the mouse over the slide area.
This also is a hybrid running a merger of some KDE core programs to support a couple of normally KDE only programs under Gnome.

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Post Posted August 31st, 2018, 8:27 am

cor-el wrote:Styling scroll bars requires "AGENT_SHEET" style sheets for full permissions and userChrome.css works as "USER_SHEET" and can't style scroll bars.

Similar thread

Try running the following code in the browser console. (run once to set style and run twice to reset style)

Code: Select all
var css = "scrollbar { width: 50px !important; }";
var ios = Components.classes[";1"].
var uri = ios.newURI("data:text/css," + encodeURIComponent(css), null, null);
var sss = Components.classes[";1"].
var type =  sss.AGENT_SHEET;
// var type =  sss.USER_SHEET;
if (sss.sheetRegistered(uri, type)) sss.unregisterSheet(uri, type);
else sss.loadAndRegisterSheet(uri, type);


* open about:debugging and enable addon debugging
* open browser console (ctrl+shift+j) in tools > web developer
* copy and paste code into browser console
* press enter to run

Browser Console command line

If the code works on Linux, then we can create a hack to run the code at startup.

Firefox Quantum compatible userChrome.js

Frank Lion

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Post Posted September 1st, 2018, 4:54 am

Having done this, both on Firefox 57-60 and at an Linux OS level, it would be FAR easier for most users to edit the OS theme gtk-widgets.css, if all that is required is a simple width change.

Incidentally, if styling the (content) scrollbars on newer Firefox, it should be noted that every code change needs the Firefox cache to be cleared before the change will show up on restart. Glad I did those 57+ scrolls, but no, never again.

NB/ Chrome scrolls are the ones you see in the sidebar, on menus, library, etc. and they're easy as you just do them in userChrome.css. It's the content scrolls (seen on webpages) that are the really difficult ones to do, post Firefox 57.
Metal Lion latest SeaMonkey & Thunderbird Themes - Sea Monkey and Silver Sea Monkey
"The only thing necessary for the triumph of evil, is for good men to do nothing." - Edmund Burke (attrib.)


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Post Posted September 9th, 2018, 8:32 am

Correction to my 2nd post above: :oops:
Have found a half dozen system and individual GTK3 packages , sorry about any confusions this caused.

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