We're calling on all EU-based Mozillians with iOS or iPadOS devices to help us monitor Apple’s new browser choice screens. Join the effort to hold Big Tech to account!

Avatar for Username

Search Support

Avoid support scams. We will never ask you to call or text a phone number or share personal information. Please report suspicious activity using the “Report Abuse” option.

Learn More

This thread was archived. Please ask a new question if you need help.

Windows FontSubtitutes rules not being followed on Firefox 109.0b7

  • 2 replies
  • 0 have this problem
  • 1 view
  • Last reply by Kotep

Kotep
Kotep
more options

I use the Windows registry FontSubstitutes (Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\FontSubstitutes) to replace system fonts like Segoe UI with other fonts. It takes a lot of work to get Windows itself to respect these options, to the extent that I have to make it believe Segoe UI isn't present by modifying a different registry location (Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Fonts).

However, Firefox does not respect the FontSubstitutes settings. Based on a previous post here, this is something it did prior to Firefox 89, but has stopped doing.

An ideal solution would be a way for Firefox to correctly read my FontSubstitutes settings. An acceptable workaround would be a way to provide Segoe UI for Firefox to use while still preventing its use in other applications. (I know that, for instance, Adobe Photoshop allows users to install fonts to Photoshop itself, bypassing the system fonts folder entirely.)

I use the Windows registry FontSubstitutes (Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\FontSubstitutes) to replace system fonts like Segoe UI with other fonts. It takes a lot of work to get Windows itself to respect these options, to the extent that I have to make it believe Segoe UI isn't present by modifying a different registry location (Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Fonts). However, Firefox does not respect the FontSubstitutes settings. Based on a previous post here, this is something it did prior to Firefox 89, but has stopped doing. An ideal solution would be a way for Firefox to correctly read my FontSubstitutes settings. An acceptable workaround would be a way to provide Segoe UI for Firefox to use while still preventing its use in other applications. (I know that, for instance, Adobe Photoshop allows users to install fonts to Photoshop itself, bypassing the system fonts folder entirely.)

Chosen solution

Could you try the workaround from back in the Firefox 89 days and let us know whether it still works:

https://support.mozilla.org/questions/1343838

Read this answer in context 👍 1

All Replies (2)

jscher2000 - Support Volunteer
jscher2000 - Support Volunteer
  • Top 10 Contributor
more options

Chosen Solution

Could you try the workaround from back in the Firefox 89 days and let us know whether it still works:

https://support.mozilla.org/questions/1343838

Kotep
Kotep Question owner
more options

Thanks, setting gfx.windows-font-substitutes.always to true still works.