Helpful info.. (I've been here before because of nonworking TFSC) and my old eyes need help, like a lot of peeps showing up here :)
First, I only use PC Waterfox 64bit 54ver. and I use Thunderbird 32bit 52ver. I have ALL my addon's turned off and not to update including WF and TB. I realize now, That Firefox and Thunderbird will never add some helpful font adjustments for our bad eyes :(
So,...
If you read through the reviews. You'll see some info reviews on how to download and install a non expiring version of TFSC on earlier version of FF, Waterfox, TB. I only wanted to help people because I feel their pain on not being able to see and need help and remember to turn off all updates that includes FF, TB, WF. . I still want to give props to the Author of TFSC. Thx you!
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it did work fine until today..... suddenly i can´t access it anymore and everything is small again.
deinstalled and reinstalled the addon but it does not appear in thunderbird 52.5.2.


don´t know if mozilla messed around again... can only say i is not working anymore. hope it will be fixed soon.
i thought the web extension stuff ony affects firefox 57??

Why the Version 56 even on Firefox 56.02 stop working !! why you do that ???? the add_on working great until this afternoon !

CAN YOU PLEASE FIX IT !

Ich finde das add-on Spitze auf Thunderbird. Aber leider scheint es auf meinen Firefox ESR 52.5.3 nicht zu funktionieren? Schade. Warum ist dies so?

Great addon firefox menus are too small to see without it.

This addon shouldn't exist there should just be a firefox option to increase menu font size but there's not, and this addon filled the gaping usability design flaw left by mozilla.

But Firefox killed it. : (

In firefox's constant quest to make a crappier version with less features and capabilities every revision, they made it so this addon will no longer function for safety reasons.

Thanks Mozilla I'm safer but now I can't see the menus. >:(

good

this sucks - there is no where to change the size of the text anywhere - so damn frustrating.....FUCK!!!

I just updated Firefox and I can't change my Theme back to what I had it on.... It's says 'disabled' and when I try to enable it, nothing happens at all... How can I fix this??

doesnt work anymore

This was a great extension before Firefox updated to the Quantum version. Most of the functionality is now gone and the extension is basically worthless.

It's currently useless. All the great features it used to provide in past versions are gone due to the release of Firefox Quantum. I hope the author finds a way to bring them back in the future.

The idea is not bad.
But the terrible behavior, when the add-on simply turns off and stops working without indicating the reasons - is very annoying.
It is understood that it needs to be updated in this case.
What for? It still working fine! I dont need any updates!
It will be easier just to install STYLISH and add a style:

@namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul");
@namespace html url("http://www.w3.org/1999/xhtml");
@namespace svg url("http://www.w3.org/2000/svg");
* {
font-size: 13px!important;
font-family:Microsoft Sans Serif !important;
}

and set
layout.css.devPixelsPerPx = 1

No longer working for the new version of Firefox.
I will review my rating once fixed, as of now, dont bother.

For all those complaining about the latest version not working (aside from the developer's action and more importantly, the handcuffs imposed by Mozilla on FF 57+ which kills and prevents many add-ons from EVER working with Web Extensions) - stay with Theme Font & Size Changer version 56, available here: https://addons.mozilla.org/en-GB/firefox/addon/theme-font-size-changer/versions/ and stay with Firefox version 56.

You can lock the current version of any add-on via the Add-on Manager: click on the "More" link next to an add-on and change "Automatic Updates" to "Off".
Firefox still alerts if an update is available but doesn't automatically update it, giving you the opportunity to check the changes made/reviews BEFORE any changes get made.

Keine Schriftgößenveränderung ab firefox 57 in Menüleiste

Wow, way to ruin a perfectly fine extension. I know it wasn't your idea to kill perfectly functioning browser, but hell, you could have just told the users NOT to use it anymore, like so many extensions do, with the new firefox.

The date bomb for this add-on is now in effect, and the add-on will no longer function in Firefox, unless you either roll back your system date, or, the instructions here may help you: http://tl.gd/n_1sqcu4r

Again, to the developer: There are XUL variants of Mozilla that people are now using, such as Waterfox and Basilisk. Please make a separate XUL based version of your legacy plugin for those users, and separate out this crippled version for Web Extension only versions of Mozilla (i.e., Firefox 57+). And please remove the date bombs, there are not the slightest bit necessary or user friendly for that matter.

Version 56 of this add-on died today. There are, however, several solutions available. You might want to check out the thread "Theme Font & Size Changer extension for FF57+" on mozillaZine.

Using Firefox 57, the extension options says "Because of the new extension system on Firefox, most of the functionality of the Theme Font & Size Changer is not available any more"...
...so why is it even available for Firefox 57 if it's not doing anything at all (definitely no changes of fonts & sizes)??

It doesn't work anymore. You can't change the font size. You can't even change the color.

the best