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Since the last update (Firefox 100), the scrollbar in Firefox fades out slowly when you don't move the mouse for a second and immediately reappears when the mouse moves one pixel. This drives me nuts as something moves on the side of text inputs or the page whenever I am trying to read something. I looked for it but found only old posts like this support article and this superuser question that don't seem relevant.

How can this behavior be disabled? Surely there's a preference for something as annoying as this?

Micropolis
  • 105
Luc
  • 3,411

3 Answers3

44
  1. Go to about:preferences or open the Firefox preferences via the UI
  2. Scroll down until you get to a section titled "Browsing", or search for "scroll"
  3. Check the setting "Always show scrollbars"

Update: bonus answer for Thunderbird which met the same fate:

  1. Menu
  2. Settings
  3. Search "Always show scrollbars" and check it

Update 2025: Latest update made some scroll bars in Firefox super thin. I've found that this can be fixed easily as well:

  1. Open about:config (type this in the address bar)
  2. Search for layout.css.scrollbar-width-thin.disabled (or, shorter: scrollbar-width also has only 1 hit currently)
  3. Double click to set it to true

Reload any page where the thin scrollbar appeared and it should become a normal width

Luc
  • 3,411
12

The precise option in about:config that configures this behavior is (at least on Windows 11):

layout.testing.overlay-scrollbars.always-visible

Set it to true to always have the scrollbar visible.

adamency
  • 503
8

I'm adding this because it might help somebody. I'm on Firefox 108 (currently) on MacOS 13.1 "Ventura" (currently). Nothing I tried was working to "stabilize" the scroll bars. I finally stumbled across something MacOS-specific, and that seems to have been the issue for me. On Ventura, the setting is in System Settings -> Appearance -> Show scroll bars.

I'm not 100% sure but I think that might have changed to hide them with the 12->13 upgrade.

Pointy
  • 887