Zen Browser 1.21.3b Patches Transparency Bug, Intel Processor Crashes
Zen Browser released version 1.21.3b Thursday, restoring a window transparency effect that a previous update had accidentally disabled for Windows users.
Version 1.21.2b had switched off the Mica effect — a Windows visual feature that blends a blurred view of the desktop into the application window — replacing it with a flat, opaque gray background.
Users quickly flagged the change on the Zen Browser subreddit, with multiple posts questioning whether the feature had been removed intentionally or lost through a settings change.
Some users suspected developers had stripped the effect to boost performance on lower-end machines. That was not the case.
Several users traced the problem to a backend configuration toggle that the update had flipped off by mistake. A workaround existed: typing `about:config` in the Address Bar, searching for “mica,” and setting the value back to true restored the effect after a browser restart.
Fix Pushed Within a Day
Developer mr-cheffy identified the root cause on GitHub and merged a patch to the main branch within 24 hours. Version 1.21.3b applies the fix automatically, removing the need for any manual configuration change.
The update also addresses two additional bugs. It patches a recurring crash affecting systems running Intel Raptor Lake processors — Intel’s 13th- and 14th-generation desktop and laptop chips. Mac users receive a fix for a bug that routed PDF files to the printer rather than saving them locally when using the system print dialog.
The Raptor Lake and PDF fixes also arrived with Firefox 152.0.1, released around the same time.
Project Growth
Zen Browser, an independent open-source project built on Firefox’s engine, said it surpassed an estimated 500,000 active users last week. That figure accompanied a separate update introducing smart tab routing, a feature designed to help users organize tabs across multiple workspaces.
The browser prompts users to install available updates when opening a new window. Users can also trigger the download manually through the release notes section in the main settings menu.
