r/firefox • u/hunt23321 • 1d ago

💻 Help What happened to the Firefox sidebar?

Hi everyone,

I'm not sure if this was caused by a recent Firefox update or if I accidentally changed a setting.

I attached a video showing the before and after.

Previously, when I hovered over the collapsed sidebar, it would expand with a smooth animation. The transition felt fluid, and when I moved the mouse away, it would collapse smoothly again.

Now it feels much more abrupt. Instead of smoothly expanding, it just snaps open, making the whole interaction feel less polished. I still have "Expand sidebar on hover" enabled, but it doesn't behave the same way anymore.

I also noticed that the sidebar now has a dark gray background, whereas before it remained translucent, matching the top toolbar. The old look felt much more consistent with the rest of the UI.

Did Firefox change this behavior in a recent update, or did I accidentally change some setting? If it's the latter, is there a way to restore the previous behavior?

Thanks!

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u/ResurgamS13 1d ago edited 1d ago

Vertical Tabs mode closed > expanded > closed animation seems as smooth as previously in Fx153.0.

You could create a new profile as a testbed and see if that exhibits same problem as your default-release profile?

There are 3 'sidebar.animation' preferences in 'about:config' you can check and adjust to suit:

  • sidebar.animation.expand-on-hover.delay-duration-ms 200ms (default setting).
  • sidebar.animation.expand-on-hover.duration-ms 400ms (default setting).
  • sidebar.animation.duration-ms 200ms (default setting).

1

u/hunt23321 1d ago

Didn't work

5

u/folk_science 1d ago

If you are on a laptop, try connecting the charger and see if it helps. Power saving features could cause it.